Jump to content


Welcome to Ultimate Subaru Message Board, my lurker friend!

Welcome to Ultimate Subaru Message Board, an unparalleled Subaru community full of the greatest Subaru gurus and modders on the planet! We offer technical information and discussion about all things Subaru, the best and most popular all wheel drive vehicles ever created.

We offer all this information for free to everyone, even lurkers like you! All we ask in return is that you sign up and give back some of what you get out - without our awesome registered users none of this would be possible! Plus, you get way more great stuff as a member! Lurk to lose, participate to WIN*!
  • Say hello and join the conversation
  • Subscribe to topics and forums to get automatic updates
  • Get your own profile and make new friends
  • Classifieds with all sorts of Subaru goodies
  • Photo hosting in our gallery
  • Meet other cool people with cool cars
Seriously, what are you waiting for? Make your life more fulfilling and join today! You and your Subaru won't regret it, we guarantee** it.

* The joy of participation and being generally awesome constitutes winning
** Not an actual guarantee, but seriously, you probably won't regret it!

Serving the Subaru Community since May 18th, 1998!

Guest Message by DevFuse
 

Photo
- - - - -

synthetic oil


  • Please log in to reply
25 replies to this topic

#1 Jack in Norfolk

Jack in Norfolk

    1000+ Super USER!

  • Members
  • 1,078 posts
  • Marblehead, MA

Posted 04 October 2003 - 05:46 PM

when if ever is this a good idea? I have heard stories of people switching later in the car's life and having probs w/ oil leaks.
I was wondering at what point (milage) people switched, and when was too high of miulage to switch.
Also, what about synthetic diff lube?
-Jack

#2 Meeky Moose

Meeky Moose

    Subaru Master

  • Members
  • 2,343 posts
  • Grants Pass

Posted 04 October 2003 - 05:50 PM

well, i had a jetta once, switched it to synthetic at 93k it didn't start leakin, it started knockin.. so i got rid of it.. last time i've done that..

my acura has had amsoil synthetic run in it since 9k. so when i got it at 164k, to ease the oil finding, i switched it to mobil 1 high mileage half synthetic 10w40.. no leaks and runs quieter than it did with amsoil :headbang:

#3 Jack in Norfolk

Jack in Norfolk

    1000+ Super USER!

  • Members
  • 1,078 posts
  • Marblehead, MA

Posted 04 October 2003 - 05:56 PM

one of my buddies switched from oil to synthetic weel before 100k and he had leaking probs on an old integra (what ever years the first body style was.)
thats why I was curious.

#4 Meeky Moose

Meeky Moose

    Subaru Master

  • Members
  • 2,343 posts
  • Grants Pass

Posted 04 October 2003 - 06:59 PM

yeah a gen1 integra was from years 86-89. mines an 89'

#5 asavage

asavage

    Eat, Live, Breath Subaru

  • Members
  • 338 posts
  • Port Townsend, Wash. 9836

Posted 04 October 2003 - 09:59 PM

Synthetics got a bad reputation in the 70's because they didn't contain the seal-swelling gunk that reg. oil does, and have almost none of the debris and waxes that reg. oil does, so seals of that period would leak if switched to synth.

Two things have occurred over the past 30 years:

* Seal materials used in cars no longer rely upon the higher percentage of volatiles in the oil -- synth. oil has very few volatiles, and has a high flash point: this combo gives much reduced oil loss through evaporation -- don't laugh, a lot of reg. oil gets used up this way.

* Synth oil designated for use in older cars do have some lighter distillates added to keep the seal materials supple.

I don't recommend using synthetic lube in units that haven't been rebuilt using newer seal materials, but otherwise I'm very pro-synthetic.

Caveat: what is being sold as "synthetic" isn't always, notably Castrol Syntec is merely a good Group III oil, and AFAIK does not contain ester/diesters or PAOs. I used Syntec from '93 until last year, but have switched to Mobil One (and, yes, I had noticed increased oil consumption over the last two years, and wondered why -- then I found out what Castrol had done). Castrol was sued over the switchover from PAO to hydrocracking (IIRC), but won the right to call Syntec "synthetic", much to the chagrine of other refiners who are using the more expensive refining method.

AMSOil and Redline are aguably the best synthetic lubes, but have the downside of their distribution channel and retail pricing; I can buy Mobil One at Costco. My local NAPA will bring in AMSOil for me, but the price is not remotely competitve. I used to maintain a "preferred" AMSOil account (it's like $20/yr.) to buy at a reduced rate, but for the rigs I drive, I can't justify the hassle anymore, and I just run the Mobil product.

#6 Brettm57

Brettm57

    USMB Regular

  • Members
  • PipPipPip
  • 92 posts
  • Whitesville, NY

Posted 05 October 2003 - 07:41 AM

I'm no chemist, just a backyard mechanic. And I know there are people that will disagree with this, but here goes.

In my humble opinion I think that all synthetic oils are a waste of money. My reasoning is this. What ruins engine oil is the dirt and contaminants it picks up rather than the oil breaking down. The only way to get rid of that dirt is to change the oil and filter. By going longer between oil and filter changes, it's just that much longer you circulate the crud through the engine. Again, I have no scientific proof, just greasemonkey reasoning.

While on the subject of oil, I experimented on my '88 hatch. I noticed that it really shifted hard when first starting out in the winter, but after it warmed up, it was fine. So I drained out the 90wt gear oil from the transmission/rear diff, and replaced it with tractor transmission/hydraulic fluid. Greasemonkey reasoning: If that oil will stand up to the work load of tractor gears and the pressure of a hydraulic system at the same time (most tractors use the transmission as a reservior for the hydraulic system), I think it will stand up to the gear load of my little Subey. It's been in there for about a year now with no problems (knock on wood!). In fact, I think I gained some performance by eliminating the drag of the 90wt oil. The best part of it is you can buy a 2 1/2 gallon jug of trans/hydraulic fluid from Tractor Supply for about $11.00. For those interested, trans/hydraulic fluid is a little heavier weight than auto tranny fluid.

OK, there's my opinion. Let the debate begin!

#7 beauregaardhooligan

beauregaardhooligan

    Subaru Fanatic!

  • Members
  • 424 posts
  • Greenville, SC

Posted 05 October 2003 - 08:13 AM

As far as oil life goes, you are probably pretty close to right-on, Brettm. It is the crud that kills the oil, although synth does hold up better.
There are gains to be made concerning performance and economy, though.
I switched FERTHER to MalWart'sfull synth (cheapest I could find) and noticed an immediate improvement across the board. Easier starts, quicker revs, and another couple of mpgs. I did extend the oil change to every 5k to help off-set the increased cost. FERTHER uses about a quart in that time.
If you're motor uses more that a quart between changes it would not be worth the cost, IM(not so)HO.
FERTHER's motor supposedly had less than 60k when installed and hasn't developed any leaks, but I could see how a high mileage motor could.
Asavage, can you tell us more about the "cracked" synth? Didn't know there was such a critter.
I understand synth is higher detergent also. I can tell the motor is getting cleaner because the oil isn't as dirty at change time as it was on regular oil. Looks like tea instead of coffee.

#8 bratman2

bratman2

    Eat, Live, Breath Subaru

  • Members
  • 465 posts
  • Aurora

Posted 05 October 2003 - 08:15 AM

Jack, I switched my Brat to Mobile 1 at 140k. I presentily have 184k with no leaks at all. I have replaced the oil pan gasket do to leaking, was leaking when I bought the Brat. I replaced the rear seal when I did the clutch as preventive maintaince since I was already there. The front seal when I put a new radiator in a couple of years ago, again as preventive maintaince. The Brat uses about 6-8ozs of oil per 3k miles and I have been changing it a 7.5k. After reading an in depth test on Mobile 1 I am changing to 10k. In the test they replaced the oil filter at 13k and saw no real reduction in oil contaminates at 14k. They ran the Mobile1 for 18k miles in a SS Camero with 1k oil analysis. I know this will start something but hope it helps you, Glenn Taylor.

#9 bratman2

bratman2

    Eat, Live, Breath Subaru

  • Members
  • 465 posts
  • Aurora

Posted 05 October 2003 - 08:28 AM

Ed, go to petrocanada's site and they will explain hydrocracked oil fully. I have seen the same things you have with star ups. Sometimes even here in eastern NC it drops into the teens and the Brat starts very easily with Mobile1. Also noticed much easier shifting with redline gear oil, totally eliminated scrapping I had going from third to fourth gear. Walmarts full syn oil is actually Quaker State synthetic hydrocracked oil. Glenn Taylor.

#10 WJM

WJM

    SUBARU

  • Members
  • 7,828 posts

Posted 05 October 2003 - 09:32 AM

Well...I just poured in some Valvoline Racing oil (only thing I had, plus it was freed from a winston cup team) into my RX when I got it, from what I could telly, everything on the engine is still original, from 133,000 miles ago. No leak. I do get some HVLA clatter sometimes, but it comes and goes...and I suspect the engine was very dirty inside. The whole car was not maintained very well. It still had original Timing Belts on it.

I have used Mobil 1 in my GL-10 since I put that 9.5:1 turbo enigne in, that was 15k miles ago. No leaks.

So who is better? Mobil 1 or Castrol?

Redline vs AMSOIL?

and what about the royal purple stuff?

#11 Jack in Norfolk

Jack in Norfolk

    1000+ Super USER!

  • Members
  • 1,078 posts
  • Marblehead, MA

Posted 05 October 2003 - 10:47 AM

are you noticing your engines running cooler? any deviations in oil pressure?

#12 asavage

asavage

    Eat, Live, Breath Subaru

  • Members
  • 338 posts
  • Port Townsend, Wash. 9836

Posted 05 October 2003 - 11:11 AM

I can't find my notes, so I'll have to make this up as I go along.

I was bribed to attend a Chevron/Texaco tech presentation last year -- free dinner, which is a pretty good way to get me to go anywhere :)

Synthetic oil is man-made, sure, but what isn't generally well-known is that it's man-made from natural gas, which is the same stuff (essentially) as all other crude oil products. That is, crude oil, when run through the conventional cracking process, yields everything from lubricating oils, diesel, kerosene, gasoline, benzene, tolulene, LPG, and CNG (as you move up the chain from heavy distillates to lighter ones).

The heavier distallates have more crap in them. They also contain more total heat energy (BTUs, watts, whatever). This is why diesels get better mileage than gasoline vehicles, and why LPG and CNG vehicles get slightly less mileage: the BTUs per unit are less with lighter distillates.

Natural gas is found, er, naturally (ie pockets of the stuff underground) and is also created by the cracking process used to make other distallates -- you can get it both ways.

Synthetic lubricants are formed by taking natural gas and using it as the base stock, instead of the heavier crude oil. The longer chains are custom-made from a natural gas base. So, instead of cracking crude up a ways to lube oil, it's cracked all the way up to natural gas (a mix of light distillates such as propane, butane, and methane), then reformed into longer-chain molecules back "down" to synthetic lube oil. This is more expensive, as you might guess.

See, synthetic oil is still organic!

The huge advantage that this has had in the past is that the end product is extremely clean -- it contains none of the waxes and crap that the original crude oil did, having been a gas at some point.

Synthetic oils then have their own additive package added, but the main advantage is that it started out about 75% cleaner than a lubricant from heavier crude stock.

The way it was presented to me (in-between the appetizer and the main course) is that sometime in the past, Chevron introduced a new hydrocracking distillation process that can produce much, much cleaner lubicating oil without having to use natural gas as the base stock. This process is called hydrocracking, and is the basis for Group III processing -- again, this is all from memory, and I might have it wrong.

Many refiners have moved to Group III refining because auto mfgrs are creating new API specs that the older refining processes are hard-pressed to meet. Even, ugh, Pennzoil has moved to Group III refining, which means that for the first time in a hundred years, Pennzoil might actually be good enough to use as a lubricant, instead of just a bonfire starter . . . but I'm not switching over just yet.

I'm going to leave aside discussion of Poly Alpha Olefins and ester/diester blend additive packages for now, as not only is it more technical, but I'd really have to go find my notes -- Sherlock Holmes, an Arthur Conan Doyle literary creation, would say that the mind is like a shopping bag, and when it gets full, in order to put something in, you have to take something out. Well, oil processes must have gotten taken out of my mind last week to put SPFI in, I guess.

Synthetic lubes do not require exotic additives to keep their low temp pour point depressed, because they're not full of gunk that congeals at cold temperature.

Synthetic lubes do not require more wierd waxes and polyesters added to increase high temp film shear and hydrodynamic performance, and to reduce volatility: they are "naturally" good at these tasks, because they do not contain the pot-pourri of crap that the reg. oil does.

Reg. oil has additives to help maintain the pH balance when exposed to combustion acids, and to help keep all the crap (and ash) in suspension. Synth. oil is "naturally" low in ash, has no crap, and is resistant to pH movement.

That said, if the Group III thing is true, then the difference between Group III refined oils and Synthetic oils has become a lot less than, say, 10 years ago.

As to the relative merits of one Synthetic product over another, in many cases it's hair-splitting to me. If you're changing the oil when you can't read the lines on the stick anymore through the oil, I don't think the actual oil is going to make a whole lot of difference except in the very, very long run. Auto engines are, by and large, designed for bonehead maintenance. Don't run dirty oil, and unless you have special operating conditions (very cold, very hot, long periods of time at more than 1/2 throttle), merely changing the oil on-time is the best thing you can do. I've already commented on Castrol's substitution of a Group III lubricant for Synthetic refining, and I positively saw a decline in performance when they did it -- but I didn't know why until much later.

Every car I've switched over to synthetic oil has seen a dramatic decrease in oil consumption -- example, '83 Chev G30 6.2l diesel, 102k miles when I got it in '93, one qt. in 800 miles consumption, no oil leaks. 80k miles later, when I sold it, it was down to one qt. in 1700 miles, still no oil leaks, average MPG over that 80k miles was 19.1 MPG.

I have other, personal anecdotes that run similarly. Synth oil Good.

I, of course, am an oil snob, and run synthetic lubricants everywhere, even in my lawnmower. I don't pretend to be rational, though. The economic payoff is very debateable.

#13 WJM

WJM

    SUBARU

  • Members
  • 7,828 posts

Posted 05 October 2003 - 11:57 AM

Excellent information!!

I run synth. in my mower too.

Id run synth in my computer....but there is no where to put it!

From my experience, every single engine I have torn down has been one out of cars that were driven daily, and taken care of like "normal" Which means, the maintinace sched. varied as was not regualar....and the innards where not too good looking. And I ve seen what inproper oil can do to and engine, and what not changing can do. I've never torn and engine down that ran on synthetic. There is probably a reason for that...hmm...higher level of pretection maybe? Therefore no engine failure!

All I know is that synths rock, and I will use Mobil 1 for a long time to come...unless I cna get my hand on some AMSOIL.

#14 asavage

asavage

    Eat, Live, Breath Subaru

  • Members
  • 338 posts
  • Port Townsend, Wash. 9836

Posted 05 October 2003 - 01:05 PM

Originally posted by Brettm57
In my humble opinion I think that all synthetic oils are a waste of money.

You are not alone in this -- many people agree with you, that the benefits do not outweigh its cost.

What ruins engine oil is the dirt and contaminants it picks up rather than the oil breaking down.

I disagree somewhat. Though the crap is the major wear factor, oil does not last forever, it does break down into other, shorter-chain molecules and as it does this it becomes something other than an ideal lubricant. Synthetic oil just takes a lot longer to do this, and has a wider temperature range where it does not appreciably "wear".

The only way to get rid of that dirt is to change the oil and filter.

Violently disagree!
AMSOil (and others; Racor?) make a really nice combo dual-filter full-flow/bypass unit for under $200.

Posted ImagePosted ImagePosted Image

The full-flow portion of the unit works as the OEM does, and does the usual/typical 20-40 micron (about .0015") filtering (BTW, filters filter better (finer) as they begin to fill up with particulates); the bypass portion filters about 10% of the oil, returning it to the sump, but filters it down to sub-micron level. Read about it, it's great stuff.

I've never installed one, but I want to, badly. Trouble is, I don't tend to keep cars long enough -- This Loyale is my 73rd car, leaving aside all the motorcycles over the years (I've got a list here somewhere). Using this filter setup, some people never change their oil, which is a possibility, though I don't know if I'd go that far. The oil stays clean.

I noticed that it really shifted hard when first starting out in the winter, but after it warmed up, it was fine. So I drained out the 90wt gear oil from the transmission/rear diff, and replaced it with tractor transmission/hydraulic fluid. If that oil will stand up to the work load of tractor gears and the pressure of a hydraulic system at the same time (most tractors use the transmission as a reservior for the hydraulic system), I think it will stand up to the gear load of my little Subey.


Tractors use sliding gears (like reverse gear in your Subaru). Sliding gears have high contact area compared to baulk rings /dogs.

Tractors don't have input shafts that might turn 6.5k .

90W gear oil (75W90, 75W140, 85W90 et al) is an EP oil (Extreme Pressure) and contains additives for this purpose. It contains sulphur, phosphorus and (boron?). The ball or roller bearings in a transmission won't care much, but bushings and bronze alloy sychronizer rings do, they have a large contact area and it's all sliding friction.

Most modern manual transmissions have gone over to ATF for their lubricant, but the sychronizer parts have been redesigned for this different friction characteristic. ATF has sturdy anti-foaming additives; tractor hydraulic fluid has much less so. Foam is bad for gears, because it contains air :). Air is an excellent lubricant, but not for gears!

(And ATF now comes in at least five broad, mutually-incompatible classes: Allison/Chrysler ATF+4, Dexron III/Mercon, Mercon V, ATF+3, the old Type F, etc. etc.)

It's been in there for about a year now with no problems (knock on wood!).


Any oil is better than no oil.

You could likely fill your trans with salad oil, and it'd work OK for a year. I doubt it it's a good long-term idea, though.

In fact, I think I gained some performance by eliminating the drag of the 90wt oil.

You could gain some performance by using 3-in-One oil and removing some of the balls in the ball bearings: you'd get better mileage, faster shifts, and your teeth might look whiter. I'm not implying that the trans will make 300k, though.

It's all about compromises.

The mfgrs have an interest in getting the cars out of warranty period without spending any warranty money on them, so they're going to expend enough engineering to do that much. The safety factor in gear lubes is huge. But gears and bearing surfaces get smaller every year, to save material cost, weight, and parasitic losses (drag). Whenever somebody comes out with a better lubricant, the mfgrs counter with smaller parts, taking advantage of the better lube.

That's why we get such a large improvement in wear when we switch old cars over to new lubes.

I had a more detailed, vebose response typed up, but I had a power failure that outlasted my UPSs; I've got to go yank out my car batteries under the desk and load check 'em, they may be too old again.

#15 Brettm57

Brettm57

    USMB Regular

  • Members
  • PipPipPip
  • 92 posts
  • Whitesville, NY

Posted 05 October 2003 - 08:09 PM

This is getting heated now! Part of my above mentioned reasoning is economics. I paid $500 for the car. My plan is to convert it to a five speed d/r someday anyhow, so if the transmission breaks, I really don't care. I bought it for a cheap toy, not every day transportation. If something breaks on it, I'll just park it in the back yard until I feel like fixing it, or else take it to the junk yard. Under the circumstances, I can be risky with my oil choices. On the other hand, if it was a brand new car, I'd follow the manufacturers recomendations right to the letter. I wasn't recommending dumping the 90wt out of your cherry auto and replacing it with hydraulic fluid, that would be crazy! I'm experimenting. If it doesn't work, it's my loss.

Perhaps I should restate my sentence; the CHEAPEST way to get rid of the dirt is to change the oil and filter. I'm sorry, but it makes no sense to me to put a $200 filter on a $500 car. Again, this car is my winter beater, it will never be a family heirloom!

Al, ya helped me out sorting out the computer on my Loyale, and I appreciate it (anybody looking to buy '92, it's for sale!). Sorry if I struck a nerve with my oil post.

.....But I can't leave without telling this. I run NOTHING BUT straight 30wt engine oil, winter and summer. Let's see where this goes!

#16 archemitis

archemitis

    guy smiley

  • Members
  • 3,554 posts
  • the big minnie

Posted 05 October 2003 - 09:26 PM

not to discount anyones opintions, but i didnt read any of the comments because i have one thing to say that i know for sure about synthetics, from experience.

MY SPFI GAINED 2-3 MILES PER GALLON WITH THE USE OF MOBIL1!

i changed nothing else, no lie, just my experience.

#17 WJM

WJM

    SUBARU

  • Members
  • 7,828 posts

Posted 05 October 2003 - 09:31 PM

Thats true...I get 27-29 mpg reguarly with my GL-10.

#18 riak2

riak2

    New User

  • Members
  • Pip
  • 5 posts
  • planet riak

Posted 05 October 2003 - 11:25 PM

What is everybodys feelings on SLICK 50 and PROLONG. They all seem to have some sort of Synth addatives...

I have used in my last car SLICK 50 oil addatives.. I used it every other oil change. Not as they indicate using it every 50,000 miles. I used this in a Chevy Celebrity 6cyl. My driving is very aggressive. I usally drive no less than 80 mph to having the speedo buried. I drive 40 miles to work one way and its not all highway driving. Its hills and alot of on and off the gas. I beat the hell outta that car and never never had a engine problem. Not even alot of oil consumption. I purchased that car with 42K and when I junked it with a trans failure it had 155K and the motor was fine. I was told this model 2.8 engine was a problem engine and no one could understand why the motor held up.
After that celebrity I had a mitsubishi mirage 4cyl with 48K and didnt use that oil addative, now I know its just a 4cyl. But within the first 6 months I blew the manual trans out and 5 months latter the motor basically was gone. Boy that 4 poper would do 105mph on a straight a way. But it didnt like it everyday on the way to work. Pontiac sunbird dead motor ,no oil addatives used,died at 123K but had 3 head gaskets done before she blew. 78 Pontiac firebird, no oil addatives used ,motor blew twice and 3 trans. 1978 chevy caprice , no oil additives used and the motor blew after a month of taking that speedo needle from zero back to zero in a full circle. This caprice had a circle instrumentaion package. My mechanic said I should be getting paid for tetsing cars for the maufactures or driving nascar. Who knows...
Now I have a Nissan Maxima and Im using Synthetic blend. But I dont think its as good as the slick 50 product.
Oh forgot about the subaru. 84 wagon that the motor never fails with that slick 50. But subies never do fail it seems. That car because of driving habits only gives me 12 to 19 miles per gallon. Oh 178K on the clock.

#19 asavage

asavage

    Eat, Live, Breath Subaru

  • Members
  • 338 posts
  • Port Townsend, Wash. 9836

Posted 06 October 2003 - 12:02 AM

When you're starting with a $500 car, it doesn't make sense to plan for the long term. Use the 30W, it nearly the thinkest oil you can buy, so your mileage suffers, it won't keep the internals as clean as a lighter oil, but who cares? As you say, it's a toy, and it'll help in marginal bearing situations or really leaky lifters or other poor oil pressure situations. Makes the starter work harder, sluggish warmup, etc.

On Slick-50: it's useless. Teflon won't stay in suspension, it's been proven over and over, DuPont distanced themselves a long way away from lube oil applications, it won't chemically bond with the engine parts, it won't do anything but get stuck in the oil filter and get taken out at the next filter change. I'm not going to cite references, you can find them via Google if you're interested, but anecdotally the company that bought Slick-50 won't even advertise it anymore, they know it's a sham.

Don't know about Prolong, and it's too late tonight for me to go read up on it. Snake oil, probably, but you folks like your "mystery" oil (which is fine for air tools, but in my crankcase?? I don't think so!).

#20 bushbasher

bushbasher

    exhaust fume addict

  • Members
  • 1,707 posts
  • Sooke B.C. Canada

Posted 06 October 2003 - 12:09 AM

my dad's 85 honda accord has almost 400k km on it, on country roads (and trips over the rockies), and it still runs like a top. It's because every time he changes the oil it is still amber. Carbon is what wears out everything (and what makes your oil black), and it comes from inefficient burning (just like black smoke, too rich). If your engine burns ideally, it will last almost forever. By the way the honda has never seen anything but the cheapest oil on the shelf. I think that other factors are what are going to change how long your engine lasts, not the oil brand or type. People just focus on it because it such an easy thing to do to your car, much easier than diagnostic testing and fine tuning of carbs and injection systems. Carbon is a major reason why japanese engines last much longer than american engines, as they are far more efficient burning.

#21 GeneralDisorder

GeneralDisorder

    Elite Master of the Subaru

  • Members
  • 20,280 posts
  • Portland

Posted 06 October 2003 - 01:27 AM

I think rebuilding engines is fun, and we need to do it so Subaru and others will keep making the parts. If our engines last too long, they will stop making parts for us. Soob engines are known to go 300k + with crappy maintenece, so what is the diff? I use Castrol 20w50, and it seems to work fine. I change it every 2k, and with an interval that short, I don't think it matters one way or the other. This isn't rocket science guys.

GD

#22 WJM

WJM

    SUBARU

  • Members
  • 7,828 posts

Posted 06 October 2003 - 06:47 AM

prolong is a sham too.

a test was done. newly rebuild V-6s, proper break in, and after that, one got the prolong treatement, to the letter. After a few oilchages with prolong in one, and the other with out, both cars were drained of oil, just like in the infomercial, and driven around a hot downtown area, with the A/C on. In the infomercial, the prolong car went for hours like this. In REAL LIFE, both cars engine's failed at the same time...minutes after the oil was drained.

#23 pianodirt

pianodirt

    USMB Regular

  • Members
  • PipPipPip
  • 80 posts
  • Seattle

Posted 08 October 2003 - 01:52 PM

When I first bought my Soob, I asked a couple different soob mechanics what weight of oil I should use, and they both replied (different shops), "10W40". I don't claim to understand the different weights and when to use what, so I am writing to hear of what other soob users in the Pacific NW use for synth oils.

I currently use Castrol 10W40 dino and am considering switching to Mobil 1 synthetic. Should I switch to Mobil 1 10W40 or a different grade? The engine has about 95kmi on it. I rarely go 4-wheeling and is mostly my daily driver with quite a bit of freeway miles on it.

#24 WJM

WJM

    SUBARU

  • Members
  • 7,828 posts

Posted 08 October 2003 - 05:29 PM

10w-30 does fine in my soobs. And I drive the RX like MAD. And you can see the motor in my GL-10 in my sig.

#25 GeneralDisorder

GeneralDisorder

    Elite Master of the Subaru

  • Members
  • 20,280 posts
  • Portland

Posted 08 October 2003 - 06:55 PM

The fact of the matter is that everyone here is pretty much correct. You could run vegetable oil or probably even a good grade of mud in a Subaru engine, and it would still last a long time. Here's my opinion's and what I have heard:

10w30: Fine for low mileage cars, but tends to be too thin for high mileage engines and often is associated with louder clacking from the hydro lifters. If you have high mileage, or loud lifters, use something heavier

10w40: Better, but I recall that this stuff has too much viscosity modifier in it, and doesn't lubricate as well as the oils with less VM in them. Also - still too thin for some of our older soobs with 150k plus on the clock. Also gets too thin when adding MMO to quiet the valves. For off-brand oils this is the one to choose tho, because their 20w50 doesn't flow well.

20w50: (specifically Castrol GTX): Flows better than other 20w50's I have seen, and has that added thickness that gives your engine much needed oil pressure. MMO can be added without the fear of making it too thin. I run this year round but we have very mild winters here, so most people probably can't do this. Other people on the board know what works best for winter (many people mix different weights)

Now haveing said that - anyone that runs 10w30 in an engine with 150k+ miles is asking for trouble. The engine will wear no matter what oil you use, and after that long, you need a thicker oil to get full oil pressure to the top-end of the engine.

GD




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users