Overdrive gear lube.

Mike J. CT

Mike J. CT

Member
I'm looking for info on the correct gear lube for 49-56 (Ford style) overdrive transmissions. I rebuild/sell these and never seem to have an answer for my buyers on the correct lube. I know that hypoid and synthetic oils are not good but not sure what actual weight of oil to use. My old Borg Warner info says 40 or 50 weight motor oil but other sources list gear oil up to 90 weight. Opinions?
Mike.
 
STA-Lube API GL-4 mild EP is easiest to get since most NAPA stores carry the stuff. API ratings of GL-5 are high EP and are to be avoided. Straight grade SAE 50 motor oil will work in a pinch. The motor oils and gear oils are rated differently in viscosity numbers. SAE 50 motor oil is same viscosity as SAE 90 gear lube so it will work.

The OEM was API rating GL-3 but that rating has been obsolete for 50-years or so. Now and then you can still find some under that rating but you really have to look for it.
 
The 49-51 Lincoln Mercury Service Manual states:
"Use SAE 80 gear lubricant for all transmission and overdrive assemblies. SAE 90 gear lubricant can be used for hard driving in hot climates. NEVER USE A HYPOID AXLE TYPE LUBRICANT."
I use a blend of NAPA SAE 90 GL-1 gear lubricant (75%) and the Lucas HD Oil stabilizer (25%) and had no problems with shifting hot or cool.
 
Lloyd Young of Ohio who is 80+ and has been rebuilding BW overdrives for most those years says GL-4 140w should be used in BW overdrives. He has a stock of OD parts and custom machines parts when nessecary.

I use StaLube GL-4 140w in my BW R-10 OD and banjo, and 90w in my ****** for better shifting (I found 140 in the ****** slowed-down the syncros too much in cool temps). I purchase my Stalube products on Amazon .... lower price and two jugs ship free.
 
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As rotorwerch has already pointed out, engine oil and gear oil are rated differently. Here is a comparison chart if it is any help for reference.
 

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I also use a mixture of GL 1 80-90 and Lucas oil stabilizer.
GL 1 does not have the additives found in modern gear lubes that can attack the brass synchros in the overdrive ******

GL 1 80/90 can be purchased by the gallon from NAPA under part #NHF 65201
 
Since the gear lube in the transmission co-mingles with the OD gear lube, what's good for the transmission is good for the OD. GL-4 90W in most temperatures, 140W in desert.
 
Minor point, but the W should only be used on 85 and below on gear lube. The W stands for Winter. SAE 85W and below are specified at 40 deg C, SAE 90 and above are specified at 100 deg C.
 
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JSeery .... Thanks for correcting that common mistake in identifying lubricants. Guess I caught the same "bug".

Paul Bennett .... Your point is correct regarding "Ford style" ******-OD combo's and I believe the Merc and Lincolns of those times were same. However my '47 coupe has what's apparently a rare surviving BW set-up. The BW OD is not part of the ****** so the gear oils can't mix. Its installed in the torque tube drive assembly about halfway between the ****** and banjo - sitting 8 inches in front of the banjo. The OD has its own bearings and seals front and rear. Its location is a benefit as it eliminates the standard bearing and seal that is normally located in the middle of the torque tube. This car came from CA where evidently BW offered these as after-market set-ups to dealers in the '40s 50's for their customers when high speed highways were becoming widely available.
 
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There was a guy that used to build up those torque tube OD set ups back in the 70s/80s but that was a long time ago now. Mitchel's are out there now so you don't see them around as much these days.
 
Mike J. CT ..... per PM, here's Lloyd's info: Lloyd E. Young, Winchester Ohio (land line 614-837-7832). Pull-up a chair, pop a beer open, and have a good conversation. Conversations with these old timer's are priceless. :)
 
Bob Green was one and Lloyd is about the only one left that works with those conversions. I heard of one that was called the Rentz overdrive but I'm not sure who did that conversion.

Volvo or Laycock overdrive conversions are out there too but more popular in countries where they are more common.
 
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