I brought my car to a mechanic and asked for synthetic oil change. However, now I have realized that mechanic has put a new sticker in my windshield that states that next oil change is due in 3000 miles. With synthetic oil range should have been 6000 miles. I called mechanic and asked if it is really synthetic and he confidently claimed that it is a simply a mistake in the sticker and I should drive 6000 miles.

Is there a method that I can use to independently verify if my mechanic really used synthetic oil and not organic oil?

This is for Chevrolet Aveo 2007 and the sticker says 5w30 oil.

  • I think you can tell by the gas mileage of the vehicle. If you were using synthetic and the gas mileage drops 5-7% after the oil change and your driving and gas is the same, you might have organic oil in your crankcase. Just my opinion. Feb 2, 2020 at 16:08

1 Answer 1


tl dr - There is no easy way to tell, as far as I know.

Once in the engine, oil is going to look like oil. Just like you cannot tell horsepower by the seat of your pants, you are not going to be able to tell what weight an oil is or what it's made of by feeling it.

You could send the oil off to a lab to be tested, but then I don't even know if it would tell you the difference.

Realistically, you have to trust the mechanic has done what you've paid them to do. That, in and of itself, is a crap shoot.

  • My impression is that synthetic and organic oil degradate at different pace. Would this also imply that synthetic oil should have less residue in 3000 miles than if it was organic. However, I don't think I have a reference point to compare my current oil after driving 3000 miles.
    – Jonny
    Sep 19, 2015 at 23:23
  • @Jonny - I don't know if I'd use the term "degrades" to describe what happens to oil. If you want to learn more about oil, go check out Bob is the Oil Guy Website. There is a lot of good information over there ... the forum, however, is a typical forum. It's the University which I'm talking about. They love Amsoil over there, too. Nothing wrong with Amsoil (except the cost), but there are a lot of other good oils on the market as well ... I'll leave it at that, though. Sep 20, 2015 at 0:23

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