Forester XT (2.0 DIT) - 5w-30 required, why not 0w-40 for track use under boost then?
 

I think the thread title is self explanatory.

FYI, I've read multiple threads regarding the oil weight for both track use and track use with FI applications. I am really surprised with the fact not so many people prefer 0w-40 weight oil for FI+track use especially since Subaru mandates 5w-30 for Forester XT DIT engines ( assuming not so many Forester will see track..) I don't remember anyone mentioned the required oil viscosity for the XT Forester http://www.cars101.com/subaru/mainte....html#forester


In other words, if a street driven Forester XT uses 5w-30 for the same engine (FI application), don't you think 0w-40 would be more protective for track use (specifically under boost)?

http://www.ft86club.com/forums/showthread.php?p=1190674

according to this thread majority of the people use 0w-20!!! for those who use 0w-20 oils in their cars, did you take a look at the flashpoints of that specific brand engine oil?

and I found out from a related thread that the service schedule shows that 0w-20 and 5w-30 can be used but 0w-20 is preferred ( probably for gas mileage)
http://i294.photobucket.com/albums/m...l/2ddd10e5.png

Using high quality synthetic fluid of the recommended grade is important. We have many Blackstone UOAs from this engine and from other engines to know that the Motul 300V doesn't breakdown even with excessive heat.

0W20 even with Motul 300V on our FA20 motors are perfectly fine. We ran 5W30 before because we were unsure what the motor should be taking with track abuse. After some data was logged, many Blackstone UOAs were performed, and many meetings with Motul, we jumped on the 300V 0W20 bandwagon and have been happy since. Running an oil cooler is definitely required when tracking your car. Even more important when the engine is boosted. Mandatory if you run turbo instead of supercharger as the engine oil generally cools the turbo.

I understand the importance of the high quality synthetic oil :) I just want to understand why so many people( even when boosted) use good quality 0w-20 oil when Subaru mandates 5w-30 for their boosted engine.. all else equal (high quality oil) I would definitely prefer the 5w-30 as a bare minimum for FI..

at certain operating temp, it should provide better protection.. what's missing here?
IIRC, all the Subaru engines (NA) come including Outback, impreza ..etc filled with 0w-20 from factory and I am pretty sure it's for the gas mileage,

Thanks again

Yes 0W20 is for gas mileage, but also means the tolerances in the engine block are different. The concern is with viscosity when there is excessive heat. I can't say for certain about for other oils, but 300V will work well. If FA20DIT recommends 5W30 for their application, then run 5W30. If the FA20 recommends 0W20, then run 0W20. Even with a ton of heat, 300V has no problem lubricating effectively. If your 0W20 oil is having issues protecting at high heat and RPM, then go up one viscosity level to ensure your engine is protected. On another note, the FA20DIT might be oil cooled hence why that oil cooler is necessary. :)

My OEM oil cooler is in my garage and will be installed with KW kit ;)
I will most likely use 0w-40 Mobil 1 European formula as I did with my previous cars (prior to that I was using Shell Rotella T6 with no problem..on everything I owned...cars, bikes..etc) .


Do you know the flashpoints of V300 (0w-20) ?

I do not know off the top off my head. Your OEM oil cooler won't be enough for track use at all. Maybe for the street it's fine if you do a couple pulls.

I will most likely attend couple events this weekend and try to get some logs with Torque App. My kit hasn't been installed yet so I will first try OEM cooler with Koyo first then upgrade if it becomes necessary,

On stock setup...you are kind of okay. The issue is added power...

Based on research, OEM heat exchangers are to aid in warming up oil and maintaining consistent temps. A real oil cooler would be the proper way to cool down oil temps.

I think Subaru skipped out on an OEM heat exchanger because...
1. 0w-20 is already pretty thin, therefore, a heat exchanger isn't necessary.
2. Heat exchanger won't really help in extreme track conditions.

For a track car, I think a proper oil cooler would be needed. Why do you think the BRZ RA edition includes an OEM oil cooler?

It's not the same engine. It's a FA20-DIT. The specifications are not the same, and the tolerances are not the same either.

As with anything else, they expect enthusiasts to swap out components with this car.

The oil cooler is a common upgrade for the WRX/STi.

I understand there are some differences but DIT engine also has stronger internals and oil cooler ( adequate or not) but still mandates higher weight oil.

You're trying to make a correlation that isn't there. Comparing a FA20 to a FA20DIT is like comparing a FA20 to a FB20...

You're welcome to use a 0W40 oil in your engine if you like, but we make our decisions based on test data and evidence, and 0W20 is what goes into our engine. A higher weight oil doesn't equate to more protection.

I am actually not :) I just wanted to use the FA20DIT as a reference simply because Subaru recommends 0w-20 oil for pretty much everything they make ( and even allows 5w-30) but when it comes to FI engines, Subaru adds ..

since they're both FA family engine made my Subaru and according to the specs FA20 ad FA20- DIT have a lot more in common compared to FB series..

Back to topic, are you suggesting a higher weight oil (made by same high quality manufacturer say for instance Motul 0w-20 vs 5w-30) doesn't equate more protection at certain temps especially under boost + hard driving?
Again, I am not questioning the quality of the motor oils solely based on their viscosity but I just want to learn the logic behind using the bare minimum that is suggested/designed for a stock (or close to stock) car when adding 60-70% more hp with FI and more importantly when pushing it to the limits (HPDE-AutoX ..etc)..