What is the best oil to use in a 1986 420SEL? (180,000 miles) 50/50 combination city-highway driving, no hard driving and oil and filter changed monthly. I am currently using Castrol GTX 5W-30 on the advice of my mechanic. He said that many of the car he has worked on needed the cams replaced too often until they started using 5W-30 oil, after which the cams lasted much longer.



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Jason Priest
1986 420SEL