This is not an oil specific question..

VCuomo

With all due respect to your friend, I don't believe this is correct. If you change your oil with oil that has the same additive package, you'll still get the same protection (it'll just come from cleaner oil).

Everything else he said - True.

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My car sees only street use, about 70% freeway and 30% street use in flowing (not stop-and-go) traffic, and in 70 - 95 degree ambient temperature. Given those operating conditions, 3K oil changes would be downright silly. I've been changing mine at 5K intervals with premium full synthetic oil and oil filters, and I'm sure I could easily and safely take it to 7.5K mile intervals (but there's no reason to, other than saving a little money, and it really is "little money" in the big scheme of things).

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