Im just curious, why dont people use oils like a 15w-40 mobil Delvac or Rotella in boats? We use it in the big rigs, and never have any oil related issues? I mean motors go a million miles or more before overhauls, and are usually running under high boost conditions, etc. However the big diesels dont turn as many RPM as a gasser.

I use Amsoil Synthetic 15w/40 Marine/Diesel oil.

I have used it before.

you know, that sounds like a simple solution to a question I have been having with myself. I use the stuff in my tow vehicle and 'they' say the oil has more longevity than others. Im going with it this spring, plus it comes in gallon jugs.... which is usually cheaper.

I run Rotella in mine 15-40

I use it as a break in oil before switching over to syn.

Diesel oil will work just as good as any coventional automotive oil. Most diesel oils sold today are "goof proof" meaning you can run them in gas or diesel engines.

However, like their automotive counterpart, they are also subject to lower levels of zinc/phosporus.

They are no better or worst than a petrolem auto product for break in.

Bottom line is they will work.

Ken

We use Rotella 15-40W as breakin oil in all our new engines as it has a much better wear package mix than most automotive conventionals and synthetics.
We recommend switching to synthetic 20-50W after break in but you could easily stay with the Rotella if you choose.

Best Regards,
Ray @ Raylar