Technical Gear Oil

I got a 61 Ford Falcon with a 3 speed on the tree manual. Getting ready to replace the gear oil and not exactly sure what weight oil to use. Tried searching online for the answer with no success. Does anyone know what gear oil I should buy, or what is recommended?

 

I suspect you will get a few different choices offered up here. Whatever you use should me an oil that is safe for yellow metals, to protect the synchronizers and thrust washers. I put a 64 Comet 3.03 3 spd manual together awhile ago and used Valvoline synchromesh oil (MTF) and it's performing well. I will add that it's not specifically recommended for that tranny. After the research I did I decided it would be a good choice.

 

C0AZ-19580-B (SAE 80) from the owners manual.
falcon1961_36.jpg (1925×1385) (carsandracingstuff.com)

 

Your typical 80/90 off the shelf type stuff will be fine. don't over think it.

 

That transmission doesn't require any type of exotic lube

 

I'm using a Richmond Gear GL4 in my Muncie, 80-90 weight.

 

Yep, planning on using Sta-Lube GL-4 in both my M-20 and Richmond Super T-10.

 

Someone steered me to the GM Syncromesh oil, but I wasn't able to find GL4 on the label, so I passed it up. At one time I was able to dredge up a Pennzoil GL4, locally I do not recall the stock number.

 

Read label, same as gm # 12345349, GL3/GL4, they redid the label a couple years ago, safe for brass. Perfect for old transmissions. Get it at AutoZone.

 

Save yourself a little money and go with a petroleum based 80W gear lube. If you're driving it in cold weather and it feels sluggish when shifting, drain out a pint or two and replace it with some ATF.

 

At operating temp 80wt. has same viscosity as 30 wt. motor oil, adding atf (10 wt.) Will lower viscosity, and may have adverse effects to 80 wt. additive package that prevents wear. Atf is used in more modern transmissions because components are designed for it's additive make up.