0-20w oil and what to expect.

[Redhat]

I've been driving a 96' Legacy for years.  EJ22 with close to 200K.  Did a valve job, head gaskets, timing belt pullies and tentioner, struts, coolant senser etc this summer and she runs great but shes old and I've been thinking of a new outback.  I wanted to hear it from you guys what the thinking is about Subaru's new issue.  Oil consumption, CVT etc.  Hoping all is well in new Subi land.

[nipper]

They all are using more oil now for several reasons. They are asking more power out of small engines so they use more oil. I think we are just all spoiled as oil consumption isnt necessarily related to a mechanical issue. Oil does evaporate as it is used not only for lubricating but cooling of pistons. 

 

The feeling of the thinner oil is to help raise the MPG. Thinner oil easyier to move, faster to warm up. What the avg owner wouldnt care about (1 mpg) is big over a fleet of many engines. 

 

It is possible that a little thicker oil would solve the problem, but unless you have clouds of blue smoke coming out the exhaust, or engines dropping valves it is a non issue. 

[Redhat]

What I've been reading on other boards is excessive oil consumption.  1 quart per 1200 miles.  Every third fillup you're adding a quart of oil.  Is this the average to expect?

[nitroman58]

I have been investigating this issue also.  I drive a 2011 Forester with a manual transmission.  When I park the car during the summer months, I detect a burnt oil smell. I hear piston knocking during the warmer weather months as well.   During the first year, the dealer told me that was normal.  I recently put a call into Subaru of America in Cherry Hill, N.J.  They told me that there should be no more than  1/3rd quart of oil for 1200 miles.  I am still monitoring this, as I have not driven that distance as of yet.  I know that there have been two class action lawsuits on this issue.    I have a co worker that told me that the piston rings on his Audi A4 were replaced at 55,000 miles (under warranty).

My wife has a 2014 Imprenza sport which does not have any oil consumption issues, on the other hand.

I feel that the thinner weight (0W-20) is at least part of the issue.   As Nipper states, it is used to improve MPG rating.  I am seriously considering switching to 0W-30 synthetic during the warmer weather months.  Currently, I have 36,000 miles on the car, so I am still within the warranty period.

I do not think that all of the newer Subaru's have this issue, however.

[keith3267]

The second number is the relative viscosity of the oil at around 210 degrees F, so the outside temperature is not a factor is selecting this number.  The number that is affected by the outside temperature is the first number, specifically if it is followed by a w.  The w means winter and that is the oils relative viscosity at 0 degrees F.

 

My understanding is that the new engines have a tighter seal at the edges of the main and rod bearings to slow down the flow of oil from the bearing surfaces.  The bearing to journal clearance is the same, but oil flows from a hole in the center of the journal to the outside of the bearing.  The gap between the edge of the bearing and the side of the journal is made smaller.  If you use a higher viscosity oil (second number), the oil flows slower, pressure is higher and the result is that the oil gets a lot hotter against the bearing surface.  This can lead to bearing damage.

 

For warmer weather, you might get away with 5w20.  But 5w20 can be made from conventional oil, a synthetic blend or a synthetic group III petroleum based oils which do not meet the standards required for use in any engine that specifies 0w20 oil.  0w20 oils must be made from group IV base stock PAO which is a synthesized oil made from natural gas.  It has no paraffin's in it.  That's important for some reason.  If you switch, make sure you are using a group IV synthetic oil such as Mobil One extended drain.

 

However, there is one more issue and that is the oil does more than just lubricate.  It is also used as a hydraulic fluid for the variable valve timing.  The wrong viscosity oil could have a detrimental affect on cam timing.

 

Bottom line, if you have an engine designed for 0w20, you should probably stick to it.

[nipper]

http://www.edmunds.com/subaru/forester/2014/consumer-reviews/review-286803830262366208/

 

http://www.subaruoutback.org/forums/104-gen-4-2010-2014/177690-use-5w-30-instead-0w-20-a.html

 

http://www.subaruxvforum.com/forum/engine-drivetrain/20153-alternative-0w-20-engine-oil.html

 

Oil viscosity doesn't really have that much to do with using it as a non compressible medium to do work for the valve train.

 

It is all emission and MPG driven.

 

http://blogs.cars.com/kickingtires/2013/08/expensive-oil-changes-are-here-to-stay.html

 

and finally 

https://autos.yahoo.com/news/consumer-reports-sees-oil-vanish-test-cars-140000066.html

[nitroman58]

Thanks for the excellent links and discussion.

If I were to trial another oil in warmer weather months, would 5W-20 synthetic be the best choice?  

[nipper]

I think the first question to ask with any new car is, do you want to keep it for 5 years or untill the doors fall off?

[MilesFox]

I would move it up to a 0w30 or perhaps a 0w40. Group IV oil can be made from paraffinic oil such as Mobil 1. You have to get into amsoils and pennzoil platinum to get into a group 5 oil. 
Good luck. 

[keith3267]

You don't use group V oil in a car.  Its not made for petroleum powered engines.  I don't know what it is used for but it is not ICE engines.  Group III is your paraffin based synthetic.  Group IV and V are both PAO oils, but you only use Group IV in your car.  Mobil One is group III where Mobil One extended drain and Amsoil are Group IV PAO oils.

 

http://www.upmpg.com/tech_articles/motoroil_viscosity/

[nitroman58]

I think the first question to ask with any new car is, do you want to keep it for 5 years or untill the doors fall off?

I usually keep a car for 10 to 15 years, unless the maintenance expenses approximate the value of the car.

So Mobil I extended performance is the one?

[Aluxes]

I use Castrol synthetic 0w40 year around in my 97 Impreza OBS. It runs awesome, it doesnt burn any oil, I never have to add any oil between changes and I go about 6000 miles using a K&N oil filter. Plus the engine has 271,xxx miles. I commute a round trip of about 1000 miles every 2-3 weeks, plus my daily driving when at home.

[MilesFox]

I have a story to tell about using 0w40 in place of 0w20 in 2013 impreza FA20. I work at a fast lube and has a customer come in for the first time at my shop with low on arrival (dry dipstick) with a presumed 5000-7000 mi interval. I prescribed an oil system flush and 0w40 oil. Well, she came back today after 8000 mi and was only down .5 qt in 8000 mi with 0w40, and having not checked or added to the oil since the first visit. Current mileage was 40,400 upon arrival this time. My recommendation and application of 0w40 comes from 40 grade oil historically being applicable with subaru, and that 20 grade oil was never called for before the FA engine. 

 

I wish i had more history with this customer's oil service to officially make any claims about 0w40 reducing oil consumption for this application.

 

Now, is there a moral dilemma to using a customer car to apply my own curiosity for results or going against API starburst 'energy conserving' oil? 40 grade oil does not bear the starburst symbol, although the oil we used does meet API SN requirements for this application. This recommendation did come with expertise with Subaru having owned them for better than 15 years

Edited January 5, 2015 by MilesFox