I have been looking over the threads on best practice for oil and oil filters and there has been a lot of back and forth.

I have an 89 supra sunsport 351 Ford pleasurecraft motor. My spec book calls for 10w 30/40. But I see alot of knowledgeable people here saying lots of different things.

Some people say use a diesel engine oil for better protection for the work these motors do underload. Some saw bump up to a 15w-30/40.

I know oil is a pretty simple thing for the most part check it, change it, and done be cheap with it and you should be good.

But for an older motor like this should I bump up the weight to 15w...is the diesel oil a real improvement? I got some new Ford oem 10w-30 wondering now if I should return it for another type???

Also, marine vs auto oil filters don't seem to be much different. Any real benefits to getting.a marine one?