84' SN Custom Craft recommends SAE W30 & Dexron II instead of 15W40 & Dexron III

[trueblue41]

Going to do my first oil and transmission fluid changes, and online the recommendation seems to be 15W40 & Dexron III, However, my 84 PCM engine manual says otherwise and recommends SAE W30 & Dexron II

Dexron II recommendation makes sense (as Dexron III wasn't available until the 90s.


Should I stick with exactly what the manual says (idk if i can even find Dexron II) or is 15W40/Dexron III just as good (if not better)

[Jonny Quest]

If that was my boat, I would run Dexron III in the tranny and 15W 40, 15W 50, or 20W 50 in the engine. I would also ensure that the oil had adequate ZDDP levels -- say 1,200 ppm or higher. In my 2 previous Ski Nautiques with SBF 351W engines, I ran Valvoline VR1 full synthetic 20W 50. Occasionally I ran Shell Rotella T6 in 15W 40.

JQ