I was wondering if I could put a heavier weight gear oil in my drive to avoid the shock that it gets from getting on plane and airing out the props. Currently running 75w90 Amsoil, but was looking at going to 75w110 to reduce wear from heat and shock...Is this a good or bad idea? I know these drives get hot when running and would think based on my over the road truck experience that the heavier weight oil would benefit. Any input?

I spoke with a Royal Purple rep and he said it would be better to keep the thinner oil cooler. Their lube, ideally, should be no hotter than 170* for best performance. The RP 75w-90 has better viscosity than the heavier lube.
You need external cooling to keep it that cool, on the Bravo drives.
I dont know about the Amsoil, but like you say, with any lube.. cooler is better.

Dick

FYI Bob Teague has been running the AMSOIL 75w-110 in his boat for the last two seasons. I have switched my bravo Xs to it also, and is what I'm recommending from here on out.

Well there you go.. some real world application. I think the RP heavy weight was 90w-140.. so we are not talking apples to apples. May be why he recommended the 75w-90 in his product..

I wonder what temps he (Teague) is running that Amsoil to?

does it have the GL5 rating?

I don't see where it says about the GL5 rating..

https://www.amsoil.com/storefront/svt.aspx

Its says its capable, The difference I see is it doesn't say it will mix with a % of water,I wonder what the rating is on foaming,neither has a rating.I know the agm foams on mine.

Irish, are you running the Bravo X or the Bravo XR?

FWIW - last summer I ran the 75-110 and I lost a couple of MPH on top. So, I have to agree with Gadgets. Keep it cool or you might lose speed.

Speaking of "cool" I thought you were coming out with an drive oil cooler Mr Gadgets...

Bravo drive...no X or XR...waiting til fall to have Mr.Gadgets beef them up...I'd rather lose 2mph than blow a drive..

The Amsoil 75w90 Marine Gear Lube says it will mix with water. I don't think even the Merc HP stuff claims it won't foam does it? I just want to save my drives 1 season til I can afford to have them gone through. This whole winter project has been expensive.