Originally Posted By: Chirs
Hi guys I'm in a similar boat (84 Supra with PCM SBF 351W) I've been agonizing over the same question, and after exhaustive reading on this site including white papers and data sheets, I arrived at M1 high mileage. Unfortunately it's unavailable in Canada.
Would others agree with this? I like the de sludging and seal conditioners, and the 1100 ppm Zinc and phos, but these motors are operated more like a race motor so perhaps something else would be better? My boat is used exclusively for skiing, so it's at or near WOT a lot.
In my case I don't care if I have to go to a speed shop to get it, I just want the right oil.
You must either be a barefoot competitor or ski slalom course with short course entries, or are an over 125' jumper if you run at WOT that much. I competed in three event up to 32 off slalom and didn't use WOT very often, even with 250 HP carbed small blocks.
The easy answer for all inboard ski boats is HDEO, any brand including Super Tech. My Nautique I bought new will see its 30th season this year, I have more exotic oils on the shelf but run HDEOs because I know they will make it last as long as it can. HDEOs are perfect for most marine inboards.