Dumb Oil weight question

[rob_and_trish]

I tried to do a search on oil weight but it seems like answers are all over the place.
I have a 350 MAG MPI - the service manual says to use 4 Cycle 25W40 Engine Oil
My buddy uses Shell Rotella T 15w-40 in his. So here is my question.
The local walmar has Shell Rotella T 15W-40 Heavy Duty Diesel Oil - Is that the same thing - (Diesel Oil?? never heard of it)....also - is normal oil the same as 4Cycle oil?
Sorry - I kind of an idiot when it comes to things like this....Im a diy'er for the most part - but and curious about this.

Thanks

[chpthril]

When dealing with diesel HD usually means high detergent not heavy duty. I would not suggest HD diesel oil. Yes 4 cycle is normal car engine oil.

[lee]

I use Pennzoil Marine 15w40.

[jimidemo]

I use exactly what the book says....Quicksilver 25W-40 or is is Mercruiser 25W-40...If I wasn't at work I could tell you..lol. Either way I follow the book even though it does cost a bit more.

[River Runner]

I tried to do a search on oil weight but it seems like answers are all over the place.
I have a 350 MAG MPI - the service manual says to use 4 Cycle 25W40 Engine Oil
My buddy uses Shell Rotella T 15w-40 in his. So here is my question.
The local walmar has Shell Rotella T 15W-40 Heavy Duty Diesel Oil - Is that the same thing - (Diesel Oil?? never heard of it)....also - is normal oil the same as 4Cycle oil?
Sorry - I kind of an idiot when it comes to things like this....Im a diy'er for the most part - but and curious about this.

Thanks

Walmart sells Quicksilver 25w-40 marine engine oil.

dont use rotella....that's a Diesel engine oil...high detergent as others have stated.

Use the weight your manual specifies.