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Old 08-19-2014, 10:02 AM   #9
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Default 2015 WRX Used Oil Analysis Thread

Originally Posted by wiUFsh View Post
geeman789, that explanation was outstanding!

I am hoping for better viscosity results next time with the 5W-30 Pennzoil Ultra Platinum. I have seen UOAs where it will maintain a 30 weight viscosity but it wasn't in the FA20DIT for the 2015 WRX.

It's possible for PU 5W-30 to remain a 30 grade, but don't hold your breath. I know there was a nice trend from a stock WRX (mainly highway mileage) a while ago with PU 5W-30 staying in grade. This is from an EJ engine:

Your best shot of any 5W-30 oil remaining in grade is to use a Euro xW-30 or adding a couple of quarts of PU 5W-40. Over time, oil can actually thicken back up but the only way to see this is uoa's every 1k miles without adding oil to replenish the sample. The highway driven WRX I'm referring to above did ~7,500 mile oci's.

I don't think I've ever seen a factory fill "5W-30" Subaru uoa come back as a 30 grade (even in an N/A Outback). I suspect the oil is an extremely light 30 grade or thick 20 grade.


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Last edited by bluesubie; 08-19-2014 at 10:12 AM.
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