Not sure what you mean. "Drive oil" is simply gear lube. Merc just supposedly adds some extra water emulsifiers for protection in case of a water leak into the drive. Any of them leaking into the water is not good for the environment.

Truck = Amsoil 10W30; also Amsoil in the tranny and differential

Boat = Amsoil Series 2000 20W50 Severe Service Racing Oil; Series 2000 75W-90 Gear Oil in the outdrive

Two reasons:

(1) There is only one true synthetic oil out there that offers straight weight oils w/ detergent in 30W or 40W (Royal Purple). Redline's 30 & 40 are non-detergent for racing only (to be changed after EVERY race).

(2) The reason Merc does not recommend the multi-weight oils is that conventional dino oils require additivies to make them multi-weight. Syn oils require very little or no such additivies unless you are using an oil with a large "spread" such as 5W-50.

That said, from what I've heard, the straight-weight blend that Merc has is the best idea of all (except that it is not synthetic). It's like having multiple sizes of ball-bearings. If somebody make this oil in a syn version, I'd be all over it. What I don't know is if creating this "blend" is as simple as pouring two different straight-wt oils into the same container. I would guess not as it seems like the heavy stuff would always go to the bottom.

Kendall Racing 20/50. Change it every 10-15 hrs. Just did a rebuild and am told everything looks perfect. No major parts needed.

I have a stock 454 Mag MPI with 500hrs. I use the merc motor and gear oil. No problems, and I drive it like I stole it!

Valvoline VR1 40

royal purple for me.....

KY Jelly has never let me down
aborbs any water you may have in your motor too

works grear in the drive too

A favorite for years KY Jelly by Johnson & Johnson is the No.1 lubricant available today

pennzoil 15-40 on the boat

On the outdrive original quicksilver outdrive oil

mobil1 5-30 on the lt-1 engine in my Jeep.

Pennzoil 20-50