Quote:
Originally Posted by Irace86.2.0
OEM turbocharged Subarus use 5w30--not 0w20. Why would 5w30 not be the minimum? Then he could use thicker oil if there are serious track days.
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I really like this logic. OEM's are forced to make so many compromises with their recommendations and design it is impossible to get one recommendation for everyone.
A 0W-20 is great for a car that isn't tracked, doesn't have a turbo and the associated heat it generates, needs to protect the engine when starting the car and driving 1km to the shops to buy some milk, whilst optimising fuel economy. 0W-20 might also be just OK for a NA car doing a hot lap or two in the overall balance of "best oil".
It's a hard compromise for the Toyota and Subaru engineers to balance all these requirements. But that doesn't mean follow the OEM book when you have a turbo and are driving hard for extended periods.
Interestingly the GT86 OEM Toyota race series in Australia a lot of the competitors use 0W20. That is because it is a fixed spec race series (oil weight is free spec) and very thin 0W20 sucks less engine power that pumping a 50w. Those extra few HP are whats needed to win and they just accept the fact they will destroy engines doing it. If you are in a competitive form of motorsport where 5HP is the difference between winning and not, then protect the engine and make sure there is enough pressure when the oil is hot.