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I think I'd shy away from the Red Line oil since it's for transaxles as well as transmissions. It's likely to contain hypoid additives for the transaxles.

This is what I’m using:


1954 Crestline Victoria 312 4-bbl, 3-speed overdrive

I have used the 90 weight "tractor transmission fluid" from Tractor Supply with a lot of success over the last several years. It is 90 weight mineral oil. Back when I was reading up on all of this I was somewhat concerned about synchronizers, some of the dialogue about modern multi-weight oils eating them up, etc. To be on the safe side I went this route - no trouble in any temperature. 







Daniel Jessup

Lancaster, California

aka "The Hot Rod Reverend"
check out the 1955 Ford Fairlane build at www.hotrodreverend.com

I’m assuming it’s the solenoid (likely needs cleaning). Plus, the issue mainly occurs at night, driving with the brights on (original 6V system).  Just may not be enough juice left over to engage 20 yrs. of accumulated gum/sludge (internal seals/contact points don’t last forever).  Since the relay is solid state converted, I won’t bother to change that now, as those electronics tend to either work or not.  Good opportunity to change the solenoid-to-trans. seal also, and fill trans. with fresh mineral oil.

6 VOLTS/POS. GRD. NW INDIANA

https://www.napaonline.com/en/p/NHF65201
This is what I've been using for about 6 years now. No issues whatsoever

Durham Missouri

You might also stick your finger into the fill port(s) and see what you pull out. How many decades since the box has been serviced?

SPEC calls for SAE No.40 weight engine oil (non-detergent) or SAE No. 80W GL-1, not a multi-grade. SAE No. 50 or SAE No. 90 GL-1 for extreme temperature operation (not snow country).

If the OD begins to operate after vehicle warmup driving, the lubricant is either fouled are too heavy.  Wear can and will result ($$$).

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What kind of oil is everyone using? I've never had a issue with overdrive engagement in cold temps.

Durham Missouri

I recently had a similar problem with the R-11 OD in my car hauler.  The fuse blew, so I took the solenoid out and took off the rear cover.  Things had a little oil on them, including a leather-like washer that was probably intended to be a cushion for the plunger.  It was sticky with oil and tended to remain stuck to the mating part.  I cleaned it thoroughly and it now works fine, hot or cold.

John - "The Hoosier Hurricane"

My ’55 Customline with the BW T85-OD trans is slow to go into overdrive when the gear oil is cold.  Typically okay in the hot summer months here in Texas but as soon as the temperature drops a little, it takes a little bit of running down the road before the overdrive will engage.  The colder the temperature, the longer it takes.   The gear oil is just too viscous for the OD to engage when the oil is on the cold side and some running down the road fixes that.  I rarely get the car out now in temperatures below 40°F which would exacerbate the problem.

Lorena, Texas (South of Waco)