Hello dear US fans, I bought a CHEVY VAN G20, built in 11/89. Engine 5.0 l (Beziner). Now that the engine oil is to be changed after numerous body changes, I would like to know what you are using in these rough engines. Is there a recommendation? I think part- or full-syntetics is certainly not so great for the old engine … Maybe you have a good tip… Thank you very much.