Could it be regular oil not synthetic mixture?
I bought used 2011Chevy HHR from dealership with 80,000 miles. It started stalling at lights. Something seemed to drag on the engine; especially if the ac was on. No engine repair engine light on. Engine would die at light when I accelerated to go at green light. Then I went to get oil change and the guy told me Chevy HHR used synthetic mixture specifically. I got the oil changed and now the engine runs great. Could it have been wrong oil causing this?
I doubt that was it.
Ageed, highly doubtful it had anything to do with the oil. It is possible the oil fill cap or something else was installed incorrectly during the previous oil change though. I always recommend if you don't change the oil yourself take it to the dealership and avoid the "quick lube" places. You might spend a few bucks more, but the dealerships have lots of experience with their vehicles.
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