Hi all I have a 89 pontiac T/A. It has a gm goodwrench 350 engine in it with about 40000miles.. The guy i bought it from said he put in mobil 1 synthetic oil in it from the start. I get the car and see the oil looks dark and dirty so i go and get it changed with mobil 1 synthetic oil. Almost right away it looks dark and dirty. I thought synthetic oil was supposed to stay clean longer?The guy i bought it from said he had the oil changed at 4000miles ago when i got it.The car runs real good and doesnt smoke at all, even at startup.Is this something i should be concerned about or is this normal for synthetic oil? Any info would be appriecated thanks.

 

what he told you might not be the same thing as what he actually has done. it may also be residual dirt in the engine, bad pvc, or leakage past the rings.

 

4,000 miles on the oil? It's time to change, unless all you do is highway driving.