Is there a way to tell that I have synthetic oil in my engine?
I recently started using Mobil 1 on my last oil change, 3000 miles later I had the dealer change the oil stating and paying for synthetic. The dealer did not perform the first synthetic oil change, a local oil change shop did that.
I drive a Z71 Suburban so gas mileage is very important and very noticeable. With the first sythetic oil change I noticed a dramatic increase in fuel economy about 80 miles per tank of gas( more for highway driving). Note, it takes 27 gallons to fill this tank(avg at the pump), thats about 2 or 3 mpg.
Now with this last oil change, I am noticing that the gas consumption is greater, like with the conventional oil. I have yet to fill up to actually test the consumption objectively but it does not look good.
Now I'm suspicious of the dealer! Is there a way to tell that I have synthetic oil in my engine? Has anyone had a similar experience? Note, the only indication that they were supposed to use synthetic is the an s next to the oil and the price, no where else is there a sticker or an indication synthetic was used.