Quick Question - What oil weight stock 1981 454

[country29]

Originally Posted by 78 Chevyrado

i use 10w40. the reason some people say to use the 15w40 is its a diesel oil and it still has (or had) some of the additives gasoline engine oil is missing. (govt Removed what we need) I don't know if diesel oil still has the zddp or whatever in it still. it helps flat tappet camshafts not wear as much.

you are correct, it still has the zddp, here in eastern AR I run 15w-40 rotella T until it gets cold, then run napa 10w30. Also for those that dont know, napa oil comes out of the same plant valvoline does, ashland petroleum in ashland ky, if you want to save a few bucks next oil change. just my .02