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In the 4 years, 48k miles, and probably 10 oil changes,
I have used 4 different quality oils and not noticed any difference.
I use a synthetic oil and change approx 5k mile intervals.
I like Reline oils but you can stick with the Mobil 1 if that's what you have been using. Dont run gear oil in your primary though. Put the gear oil in your trans. I like ATF in the primary but everyone is different.