According to my manual proper oil for this engine would be(for above 50 F) SAE 15W-40 GF-4 SM. On the engines oil filler cap only states SAE 15W-40 and SJ. SAE 15W-40 GF-4 SM oil is very hard tofind,as marine grade like quicksilver can not find at all. How different in fact are these engines to mercruiser, that has different requirements? asume its a GM marine block and it has vortec heads, wonder if the heads are somehow different from what GM produces for mercruiser? In any case wonder what oil You are using on these engines ? On PCM home page they only inform in the FAQ sektion like this " When the average temperature is above 50 degrees F., use a good quality SAE 15W-40 "SJ". So can forget about the GF-4 requirements?
Thanks for any feedback on this
Thanks for any feedback on this