2008 Chevy Equinox,6cycl, sport engine
<br/> Is it ok to switch from synthetic blend engine oil back to regular engine oil? What about full synthetic engine oil? The dealership we took our car in for unrelated service changed the oil even though we declined the oil change special. The car's readout showed the oil life at 87% good, it was just changed in Nov 2009. The dealership changed the oil back to regular oil on 30 Dec 09. I wanted them to show me proof from GM or give me a letter stating they accept responsibility for any related problems for the switch, they refuse to do so. The car is still sitting at the Dealership as I refused to accept it back until the matter is resolve. The Dealership stated,"well the car wasn't driven and they'll change the oil back". I said, I still want proof or the letter. Before this the service writer stated it's OK to switch oils back and forth. So what's the big deal about proof from GM or the letter I asked for??