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72k too late for synthetic oil?


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13 replies to this topic

#1 Spiffy

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Posted 19 December 2003 - 12:29 PM

I've heard some people say that it's not a good idea to change to synthetic oil after too many miles... well I've got 72,000... not sure if this mythical mileage limit applies to my 2000 Legacy GT...

what are your thoughts?

and if I switch are there specific steps I should take to transition over?

also, what's your reccommendation for brand/type of oil and filter?

I'm a pretty hard driver... I'd like a balance of protection and performance...

#2 99obw

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Posted 19 December 2003 - 12:47 PM

I think that is a myth.

I switched our outback from Pennzoil to Mobil 1 around 70k. It leaks/burns some oil, but it seems like all of my cars leak/burn oil. All cars will eventually leak oil, especially Subarus.

Most of the oil geeks at www.bobistheoilguy.com recommend using AutoRX to clean the old junk out before switching to synthetic. Don't use a solvent based cleaner that cleans in 5 minutes, bad idea.

I prefer Amsoil. It is a good oil. Mobil 1 is a good oil too, but I think it is too thin. Amsoil is a bit hard to get, but if you buy the preferred customer membership and order a bunch via the internet the cost is slightly more than Mobil 1.

I use the Amsoil oil filters. They are a good filter. Napa Gold and OEM (Purolator IIRC) would be my other choices.

#3 Warp3

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Posted 19 December 2003 - 01:11 PM

Motul is really good stuff too (thought not as cheap as the Mobil 1). Plus last I heard Motul is what the SWRT Rally cars run (or at least they have those decals on the car...lol).

In fact, I'm currently running Motul in almost all the systems on my 99 2.5RS (except the Motul coolant...that stuff is too expensive...lol). I've got Gear 300 in the tranny (and will also be putting it in the rear diff next time I change it), Synergie 6100 10W40 in the motor, and RBF 600 in the brake system.

I currently get my Motul products from Teague's Auto (also known as Boxer4Racing):
http://www.boxer4racing.com

Also, keep in mind that since synthetic oil flows easier it also flows through leaks easier. This is one of the reasons for all the "don't use synthetic on old engines" rule. If the car has a slow leak but they don't realize it with dino oil since it's thick enough to mostly stay put, then they switch to synth, suddenly the problem can be made a bit more obvious...LOL :-)

#4 Warp3

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Posted 19 December 2003 - 01:15 PM

As for filters I prefer the stock Subaru/Purolator filter for various reason (anti-drainback valve, good quality, etc.) but otherwise just avoid the real cheapies (Fram, STP, etc.) as they use lower quality materials and don't have as strong a construction (this is especially true on Subaru engines which run higher oil pressure than some other engines).

I'm not sure how much I believe it, but my dealer has mentioned cases where some of the cheaper filters have literally exploded on Subaru engines due to the oil pressure.

In fact, Amsoil filters are also great for this for one reason. They have VERY thick outer casings compared to many of the other oil filters out there.

Personally, I'm currently running a Subaru/Purolator on my 2.5RS and a Bosch on my RX.

#5 DerFahrer

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Posted 19 December 2003 - 03:50 PM

If your engine can run synthetic without leaking or burning it too much, then yes you can, and yes it will be beneficial. The major plusses to synth oil are lower friction characteristics and resistance to breakdown, or sludging.

However, my cars are too old and have too many miles, as I'm learning with my Legacy.

I use the classic L14460 Purolator oil filter on my Legacy, I believe (as others have said) that it's OEM. Bosch filters are simply trash, I'm afraid. They're made by some el cheapo company in Timbuktu and only badged as a Bosch. I used a Bosch filter once and after breaking a filter wrench trying to get it off (only hand-tightened) I said no more...

#6 SevenSisters

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Posted 19 December 2003 - 06:49 PM

Synthetic oils are good from all I've read and heard. Conventional oils are also good. I bet the guys with 300K miles on their 'ru's are running conventional oils. Synthetic oils probably last longer under optimal conditions, but fuel contanination and the like will probably make you want to change your oil at about 5K miles anyway and negate the inherent benifits of synoil.
Some users have complained about leaks, but at only 70K, do it if you want.
By the way, the only leak I have with conventional oil is at the O-ring on the filler tube and some day I'll fix it.

#7 myles

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Posted 19 December 2003 - 08:43 PM

Originally posted by Warp3
As for filters I prefer the stock Subaru/Purolator filter for various reason (anti-drainback valve, good quality, etc.) but otherwise just avoid the real cheapies (Fram, STP, etc.) as they use lower quality materials and don't have as strong a construction (this is especially true on Subaru engines which run higher oil pressure than some other engines).

I'm not sure how much I believe it, but my dealer has mentioned cases where some of the cheaper filters have literally exploded on Subaru engines due to the oil pressure.

In fact, Amsoil filters are also great for this for one reason. They have VERY thick outer casings compared to many of the other oil filters out there.

Personally, I'm currently running a Subaru/Purolator on my 2.5RS and a Bosch on my RX.



Is the Purolator 14460 identical to the Subaru-branded filter?

#8 99obw

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Posted 19 December 2003 - 09:25 PM

Originally posted by SevenSisters
Synthetic oils probably last longer under optimal conditions, but fuel contanination and the like will probably make you want to change your oil at about 5K miles anyway and negate the inherent benifits of synoil.



I disagree. IMHO unless a person does excessive idling or has an engine management problem, fuel contamination will not determine the end of life of a synthetic oil. More than likely it will be TBN (total base number) or insolubles that determine that. TBN is a measure of the oil's reserve alkalinity. As acidic combustion byproducts are neutralized by the oil the TBN falls until the oil must be replaced. Amsoil 10w-30 has an initial TBN of 12.34, while Mobil 1 has an initial TBN of 8.57, and Pennzoil 7.40 (all according to Amsoil). I think oil needs to be replaced when TBN reaches 2-4. Insolubles are simply the "crap" in the oil that the filter doesn't remove. Of course scientific analysis is the only way to know when an oil is worn out. I find that analysis doesn't make sense for me, so I have been changing the Amsoil every 7500 miles, certainly a very conservative interval. I think I have my courage up to do a 15,000 mile interval with 7500 mile filter changes this winter.

#9 Commuter

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Posted 19 December 2003 - 10:50 PM

Is the Purolator 14460 identical to the Subaru-branded filter?


I know I have the full scoop on this somewhere. I'm working a bit from memory. And my infromation is about 1.5 years old as well.

As I recall, there are "slight" differences. The Subaru OEM filter does not have an anti-drain back valve since this filter is vertically mounted on the engines. The O-ring was different too. The Subaru has a rounded contact surface and the 14460 has a square cross section gasket. The filter element looked to be identical (but there may have been a few more pleats in the one... can't remember).

In other words, the Subaru Purolator looks to be essentially the Purolator filter made to a specific spec for Subaru.

In my opinion, if you want a step up from either of these, buy the Purolator PureONE filter (PL14460). It employs smaller synthetic fibers in the filter media, which traps smaller particles. It has more pleats (surface area) as well. It's expensive, but you can get a good deal if you buy 6 or 12 (a case) at a time.

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#10 99obw

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Posted 20 December 2003 - 07:23 AM

Based on the results of this interesting test I personally would hesitate to recommend the PureOne, (GASP), the Fram did better. It looks like the Napa Gold is ok, and the Mobil 1 looks pretty darn good. I wish the guy had tested an Amsoil SDF, but I would expect the results to be similar to the Mobil 1.

#11 Warp3

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Posted 20 December 2003 - 11:41 AM

Yes, but as was brought up in that test, the methodologies were abnormal (i.e. adding "dirty oil"...how do we know they all had the same amount of contaminants to start with), the testing period low (500 miles...many filters filter much worse after becoming clogged (ie. they allow too much oil to bypass filtering when clogged) and this issue may not show up in a 500 mile test) and more importantly the driving conditions were variable...perhaps the conditions were dustier during the Purolator test leading to more contamination in the system. Besides K&N's aren't exactly known for great filtration, they are known for flowing a lot more air (every test I've seen had paper and foam air filters well ahead of the cotton gauze type in actual filtering ability). The results under more controlled conditions with a paper or foam air filter might have been significantly different (though I do think that Mobil1 would have still won against the other direct replacement filters as they make great filters).

#12 rallynutdon

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Posted 24 December 2003 - 03:59 PM

I bought a used 87 Ford van with 176,000 miles on it. Of course I have no idea what the previous owners(s) did. Since I wanted it for towing, I have been putting in Amzoil synthetic ever since with no issues (now over 200,000 miles).

#13 FoxRox

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Posted 28 December 2003 - 11:23 PM

Sunth-oils do a much better job at cleaning dirty engines and keeping clean ones clean. Usually there is no reason to run any type of oil/crankcase cleaner before the changeover. Where syth-oils take a bad rap is when it starts cleaning the dirt in an engine that is clogging up oil leaks. Most oil leaks are easy to fix. There is no reason to not change over to synth oils at almost any mileage, except on initial break in. I just purchased a new '04 Turbo Baja and as soon as I hit 7,500 miles (maybe 5,000) I'm going to synthetic oil (RedLine! or Royal Purple are my favorites) and stock oil filters until I know I have found something better.
I've seen MANY Corvette engines pulled down that have always used syth oils (usually Mobile One), and in almost every case, you could still see the original factory hash marks in the cylinder walls. Usually the bearing were in great shape. No significant wear at all internally. (These engines were being pulled down for performance enhancing rebuilds)
By all means, if you want to go to synth oil, do so! I always keep my oil change intervals at 7,500 miles nominally.
I use syth oils in all my cars, in all areas (i.e.- tranny, engine, p/s, etc.) and have never looked back.

#14 meep

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Posted 29 December 2003 - 04:23 PM

Dump it in, enjoy it.

Our 97 went 10,000 miles between changes and was really, really happy about it. M1 does get thinner as it ages. You'll know it's time if your valve clatter is increasing. I could go up to 12,000 before they'd starting talking to me. The standard 911 interval with 6 qts in the sump is 15,000 miles.

Synth has more detergent than dino oil, typically, which is why its' cleaner.

Also, instead of a 5 min flush, run 1 qt of dexron ATF in the motor for a few days instead. It's a 5-30 base oil, additivies focus on detergent and rubber protection instead of oxidation inhibitors, etc. It's fine for a short while and WILL clean the motor.

BTW-- I like Royal Purple products, but their scores are starting to equal that of the better dino oils, a bit below Mobile, which is being surpassed by a couple of the others (see the BITOG study in the other current oil thread).

Have fun.

Mike




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