A way to tell if mechanic used synthetic or organic oil?

Question

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.

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.