Hello bitog. I have a 2005 Subaru Impreza Wrx. Intake, turbo inlet, intercooler y pipe, Up pipe, Down pipe, Catback, Cobb stage 2 tune. I like to drive my car hard from time to time, and I also love my car to death. Therefore I would like a good oil. I have heard 5w30's can be bad for these engines due to shear thanks to the turbo (+mods +driving hard). But, I have heard the "better" 5w30's are more stable and shear resistant. If I went with Amsoil, should I use 5w30 as Subaru recommends, or a 5w40 as most Subaru tuners recommend? If I were to use an Amsoil Euro car formula 5W40, would I be best of with low SAPS, mid SAPS or full SAPS? First oil change after buying this car I used Mobil1 syn 5w30 and oem filter. Then I read all the horror stories with 5w30 on these cars and switched to Mobil1 0w40 euro and oem filter for the past few changes. Seems like both my engine and self like the M1 0w40 over their 5w30. Go through about 1 qt every 3k mile oil change. That is why I am curious about the Amsoil Euro 5W40, or if I should just use Amsoil 5w30. Lastly, would it be bad in any way to mix the Mobil1 0w40 Euro and the Amsoil 5w40 Euro? Say I use the Mobil1 0w40 for the oil change, and use the Amosil 5w40 as a periodic top off (go through about 1 qt every 3k mile oil change). Would that be alright since they are both pretty good euro w40? Or is mixing oils like that bad if you really care?