Oil for gear box

I have Borg -Warner 71 C gear box. The book says use SAE 90 EP for tropical regions. But then it states for earlier gearboxes should use high grade SAE 30. My is a 1978 Prairie. Can some one help.

Most (including me) use ATF and a good reason is it's high level of anti-foaming additives. Much lower visvosity too so heat buildup would be less also. And one would think clutches and gear oil pumps would work better w lower viscosity. I'm usually a fan of higher viscosity oils but w this transmission lower gets my vote. A BW working at high rpm consumes 5hp to run the oil pump and probably that number was for running ATF so 30wt would likely be considerably higher.

I had my BW rebuilt by Harbor Marine in Everett WA and they recomended ATF.

I use 30W.....the manual states for lower rpm..it is actually preferred over ATF.

Not all manuals state that.

J Lenard has some pretty good info on all this and I believe he runs some kind of synthetic in his...might be an ATF...but not sure.

My gearbox has between 7 and 10,000 hrs on it with 30Wt...so it can't be all bad....can't pin down whether the PO ever rebuiltb it

Borg Warner Model 71C Manuel

Guys I found copy of Manuel on boat diesel and it states to use Dextron Type F. But if the engine is not operated over3000 rpm you can use a high grade 30 weight oil. Guess I'll try and get some out to determine what has been used. Might just change and put the Dectron back in.

I use type F as well. It's what was on the boat when I bought it, And after survey recommended to change out the 'brown, thick, burnt smelling' tranny fluid. So it has run about 50 hours so far and been fine with atf.

captbuddy said:

I have Borg -Warner 71 C gear box. The book says use SAE 90 EP for tropical regions. But then it states for earlier gearboxes should use high grade SAE 30. My is a 1978 Prairie. Can some one help.

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I say going by the book is usually the best practice. In your case, the book seems a little vague, but to me, 1978 would be an "earlier" gearbox.

Are you in a tropical region?

I took a sample and it's red so I assume it is ATF. I will be topping it off with ATF. Thanks Guys

The guts of a BW VD are basically the same as the guts of a car automatic tranny. All references I have seen for fluid is ATF, with SAE 30 acceptable too. Never heard of anyone running gear oil. On local ones we run some version of Dexron.

My VD manual states ATF preferred, SAE 30 acceptable. ATF is available, so I use ATF. I suppose if I used SAE30 in the engines I'd have a bit of incentive to use that, but I don't.

Ken

All ATF's are not created equal. Get with someone who really knows and find out the correct one.

The Velvet Drive manuals state exactly which ATF to use.

Problem with older boats like his and mine, they often did use eng oil in the tranny and the manual makes no mention of ATF or,, they used a now discontinued ATF and thus the manual may not have proper info.

Dextron III in my VD 71C.

Our 454 gas engine assistance tow boats with VD trannys used 30wt.


Those trannys saw probably at least 20 years of abuse every season, and only got the oil changed maybe every 3 years or so on average.


My trawler has used 30wt for 30 years and way over 5000 hrs....maybe double that.


Maybe ATF is better....cant prove it by me