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Old 02-11-2013, 03:32 PM   #15
Art
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City: SF Bay Area
Vessel Model: Tollycraft 34' Tri Cabin
Join Date: Feb 2011
Posts: 12,569
Quote:
Originally Posted by Marin View Post
Tom-- Some people have said that the same lube oil they use in their engines can be used in their BW Velvet Drive transmission and some of them do this. I assumed this was correct but I just went to confirm this with the BW VD manual on the GB owners forum and found that in the "recommended oils" section only ATF is listed.

Now I know manufactures' recomendations can change over time-- for example our 1973 FL120 manual specifies ONLY single weight lube oil but later versions of the manual include some multi-vis options-- so it may be that the 30 wt lube oil in the BW VD manual is a later (or earlier) option. I seem to recall seeing it in the VD manual that came with our boat as an "if necessary" alternative but I'm not positive.

In any event we run the recommended ATF in our transmissions.

I was pleased to see Marin's statement quoted above, re his using ATF. While reading this thread I was surprised to see ongoing recommendations of motor oils used for trany fluids (although BW trans manual quote at bottom explains why some boaters use engine oils).

Via two master marine mechanics and two marine transmission rebuild specialists (all four renowned in this geographic area), as well as a few good ol’ decades experienced power boat pros... I carefully researched what was the best fluid to put into our Tolly’s C71 Velvet Drive Borg Warner tranies. Dexron II (GM) and Type F (Ford) ATF are neck and neck as the best fluids to use. I gained information that to reduce wear and get the longest duration before trans overhaul in BW trany (C71 and C72 models) their plates need the best immediate friction capabilities at each instance of initial coupling into gear while engine is at idle rpm. Therefore, as experts explained to me, the best, correct ATF fluids extend trany lifespan.

BORG WARNER C71 TRANSMISSION MANUAL OUOTE

“Type of Oil: TRANSMISSION FLUID – General Motors Dexron II and III, Ford Mercron, Daimler-Benz 236.6, or any SAE 10 hydraulic oil that meets Allison 3, Caterpillar TO-2 or equivalent specifications is recommended. Do not mix brands of fluids.”

“If engine does not exceed 3000 rpm a premium SAE 30, API-CD engine oil is acceptable. SAE 40 and multi viscosity oils are not recommended.”
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