Looking for some feedback concerning what oil to use in a 1988 292SR1 with 800+ hours. Engines are 454/330's. Just purchased and previous owner use Mercriuser 15-40 regular oil. Any comments and/or suggestions on brands or type of oil woud be appreciated. Thanks

You need to search the forums, there has to be two or three current forums discussing the same thing.

I would (and do) run shell rotella 15-40w and add some stp oil treatment or an equal additive with high zddp content. The flat lifter cams absolutely must have the heavy metals that todays modern oil no long contain. The advent of emissions standards and roller cams made oil companies remove these components of the lube, but diesel oils still have them. Although they are reducing them there too. The important part is adding the zddp (zinc and phos) to what ever oil you run.

You shouldn't add anything to an oil. If it was supposed to be in there, it would be already! Also, what happens if you add to much of that so called Zinc additive? Ever hear of oil foaming? Thats exactly what will happen and then you lose all protection! Find yourself an oil, yes a diesel oil has a lot of Zinc and Phosphorus still in it, or a racing oil and use that. Would you add an extra egg to a cake recipe because you thought it would be better? Oil manufacturers spend multi millions of dollars on their "recipes", and adding outside agents can mess those "recipes" up!

Only problem with that theory is most of the oil manufactures were forced by the government to remove the additives. Since all of the new cars use roller cams they don't care about all the older engines anymore. I have switched mine over to roller but there are a lot of flat tappet cams out there. I have been running the Amsoil 15-40 marine/diesel oil and seems to be working well.

What about using a synthetic oil like Mobil 1?

I read in another post that Griff uses Mobil 1 in his motors...

How many engines have you personally built, ran under extreme condition, then dissassembled. If it is more that I, I concede. Aside from that, why do you think zddp additive exist? You clearly have no clue regarding flat tappet 1988 cams and what it takes to make them live.

Hurray for oil threads !

Synthetics are good if you run higher oil temps than about 230f and run roller. But if you have a 1988 flat tappet cam, add the zddp for sure or you will regret it.

Right there's your answer.