Originally Posted By: HorseThief
Wow, a lot of responses! - sorry I kind of spaced on the boat and this thread for a while. Only reason Im kinda set on sae 30 is because that's the gospel that is preached by every engine builder and shop in the area. With the way it's propped and loaded it gets run around 3200-3600rpm for about 12-20 mins across the bay to our cottage with a 15 minute putt down/up the river before/after respectively.
To answer some other questions it is carburated and oil is usually changed seasonally - boat averages less than 30hrs a year ( like I said, it's for transportation, it's not the destination).
I always see the Quicksilver 25w40 and I'm tempted to use it and I'm sure there would be no issues, but when factoring in cost (delo is much more attractive!), it's lived it's easy life on a steady diet of sae 30 thusfar with no issues. I was more concerned with lower zinc levels in modern oils and TBH, don't know enough about the 5.8l cobra/Ford 351 to know if it would benefit from a supplement.
So an HD 30 would be suitable as well then? If so, then that makes things quick, easy, and cheap - which all equals more time on the water and more beer money.
Honestly, I'd run a 15w-40 or the Mercury 25w-40 in it over an SAE30. Ours is 310HP, and I spin it past 4K regularly, which is perfectly normal duty for this mill. Yours doesn't appear to be a roller motor but since it doesn't spin as high, I still wouldn't be concerned. We used regular 5w-30 in our 888 and it had thousands of hours on it and we had no valvetrain issues. It topped out at about 4K, but was regularly run at 3,200-3,500RPM.