Re: oil and oil filter
I was out on a friend's boat about 5 years ago. The alarm buzzer went off, checked the dipstick and no oil was touching it. I'm guessing it was a no oil pressure alarm. Took 5 quarts of oil to get it back up to the mark on the dipstick. The boat was 8 years old, he bought it new and never changed the oil or filter. It was still running great when he sold it 3 years later, still never changed the oil or filter.
Moral of this story is, if you don't want to use what the factory recommends, you can pretty much use anything you want and not worry about it.