The Classic Cadillac Forum Discussion, Oil Viscosity 1981 Eldorado 6.0 in Past Cadillac Vehicle Discussion; I'm using synthetic royal purple oil in all my vehicles. Based on the temperature chart in the manual and the ...
I'm using synthetic royal purple oil in all my vehicles. Based on the temperature chart in the manual and the temperatures I experience in California, it says to use 10w-40. I have two other newer cars that use 5w-30 and that's what is available right now. Will I get any benefit out of purchasing new, thicker oil? Or just use the 5w-30? The oil in there right now is clean and can wait another week for more to come in the mail, should I go ahead and put 5w-30 in there or wait and order another viscosity?
Most new vehicles want the 5w-30 oil. But the 6.0 in your 81 is a bit different. It doesn't have a roller cam like newer cars do for one thing. However, I don't think the 5w will hurt, but 10w is what the manual says and that's what I'd go with.
Just me tho..