Cadillac CTS First Generation Forum - 2003 - 2007 Discussion, Brand of oil in Cadillac CTS Coupe, Sport Sedan and Sport Wagon Forums; 2003 cadillac cts almost reaching 100miles wondering what kind of motor oil is good for these cars....
A worn engine? Have you disassembled it and measured bearing clearances??
Viscosity requirement does not change with mileage. Recommended "summer" viscosity, as stated in the owners manual, spec'd by GM power train engineers, is 10W-30.
I meant the engine with high mileage. Forgive my Google translator, he speaks English worse than me)))
I by the way I choose for my engine oil. And by the way the last thing I pay attention to the viscosity. for me more important specification institutions, chemical bases and additive packages. As well as the results of analyzes of waste oil.