bertram31.com

Granted this was performed for Amsoil, but it is still pretty impressive. I know some gears use ATf and some use gear lube, so I thought this would interest you guys! I use Amsoil synthetic ATF in my Velvet Drives.

http://www.synthetic-oil-tech.com/Gear% ... 0Paper.pdf

The gear lube in that study was for differentials.
Just wanted to point that out so nobody dumped 90w in their tranny.
Btw as far as that study goes, some manufactures require a friction modifier to be added to the differential lube. Some of the synthetics say it's already in the oil, don't believe it unless you want an expensive repair.
Some manufacturers have also increased the weight of the gear lube.

The only marine gears I saw that used a hypoid 90'or better lube were old mechanical lockup types of gears.
Otherwise it's ATF or non detergent engine oil.

Bruce you're right on with the friction modifier in particular the limited slip differentials. We have the large drums of Chevron gear oil rated for limited slip and if we do not add the Toyota or equivalent all trucks will be back with a limited slip clutch chatter at low speeds around turns. This has happened to a few Jeeps that have squeeked there way into the shop also.

Sorry, didn't mean to mislead anyone! Thanks for pointing that out Bruce.

Rawleigh,
your intentions we're honorable sir.
I had already got an email about the post and needed to clear it up.

Bruce:

Do you recommend a synthetic ATF in a velvet drive or is a traditional ATF the way to go? Any thoughts?

Thanks, Mark