Engine oil Castrol or AMSOIL
Just finally did my yearly oil change on my old faithful 04 wrx 177k miles last week. Put 14,370 miles on the signature series 0w40. Oil sample got in today. 31% oil life. Very little brass, relative clean oil. Waiting for my rod bearings to die but if this keeps up they might last a bit longer! Keep in mind I was using amsoils 25k mile oil filter aswell.
I run the OE Castrol because I still have CPO warranty for another year.
0w40 signature series amsoil. Went 9100 miles of hard, extremely hard miles 73% oil life remaining. Filter changes every 5k. Use it in all my turbo cars now.
Performed the oil and filter change this morning along with a good inspection of the top and bottom of the motor. Everything looked great, nice and clean.
Castrol is notorious for getting dirty very fast (detergents is the popular explanation). Why I like Mobil 1 a lot, doesn't discolor nearly as fast and still a very good synthetic oil.
A rotary engine builder in my city with 30 years experience absolutely swears by Amsoil XL 5w30. So that's what I use in my RX8 now.
For example- my turbo used to rattle just for a second upon startup, I always thought this was just because the oil drained out and the pressure needed a sec to catch up when starting - but with the Amsoil its whisper quiet - almost like it creates a film and stays there ready for the next start. There's a few other minor good things about this oil that I've noticed - that's just one of them. Really highly impressed with Amsoil.
Amsoil dominator 15w50 Cold (15c ambient) start up pressure = ~70psi Warm (200f) idle pressure = ~35psi Max hot (~270f) pressure @ 5th gear WOT = ~87psi and it holds steady Cruising on the highway (220f @ ~3k RPM) I see ~65-70psi Everything is well within factory spec with added protection, less consumption, proper flow, and better high heat retention. I'm gonna stick with Amsoil for a while.
Castrol Magnatec 5w-30. Love me some Castrol.
I ran this for 200k and ways very happy with results. Had the oil tested twice in a lab and was happy with the results.
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