I'm about to switch to synthetic oil on my 2007 stage 1 STi and have been reading up on the oil issues people seem to be having with modified cars and 5w30 oil. I have been advised by some friends/techs to look into a 5w40 synthetic oil but haven't been able to find any recent UOA on them. I searched but did not see what I was looking for that was newer then a year old.
Does anyone have a UOA on Royal Purple 5w40? I'm also looking for UOA on 5w40 valvoline and even mobil 1. I did find a 5w40 UOA on valvoline but the thread was about a year old lol.
Any thoughts, advise and UOA you all can give me would be appreciated. My 07 is stage 1 for now. But that will change.