As I mentioned earlier, I am new to the Forum as just having bought a 1946 Ford 1/2 Ton Pickup and I need to learn alot. My truck is a 10-15 year old restoration.

I am changing the fluids in my 3 Speed Transmission & Rear End. It sure doesn't look like the previous owner bothered.

I'd like to know what Name Brand & Weight Gear Oil is acceptable to use in my truck's tranny & rear end?

Also, what brand of brake fluid is proper?

 

I am using type 4 80/90 in trans and rearend. The trans is '46, rear is 8 in. Dont think the brand matters.

 

In fighting with a similar problem I came across this:

GEAR AND SYNCHRONIZER WEAR PROTECTION
Most manufacturers of manual transmissions and
transaxles recommend an 80W or 90W GL-4 lubricant.
GL-5 gears oils which are required in hypoid differentials
are not used in most synchromesh transmissions
because the chemicals used to provide the extreme
pressure protection can be corrosive to synchronizers,
which are commonly made of brass or bronze. Typically,
the use of a GL-5 lubricant in a synchromesh
transmission will shorten the synchronizer life by one
half. The extreme pressure requirements of spur gears
and helical gears found in transmissions are not nearly
as great as found in rear-wheel drive differentials. A
GL-4 lubricant provides adequate protection for most
manual transmissions, unless a unique design
consideration requires the extra protection of a GL-5.
The reason that many manufacturers have made
recommendations of motor oils or ATFs is that petroleum
80W gear oils frequently do not shift well at low
temperatures. Motor oils and ATFs are much more fluid
at lower temperatures and they are not corrosive toward
synchros, but they provide very poor gear protection.
These lubricants provide almost no extreme-pressure
protection. In addition, petroleum multigrade motor oils
and ATFs have very poor shear stability. The shearing
action by a manual transmission on thickeners is much
worse than in an engine or automatic transmission.
Within 5,000 miles the thickeners can be rendered
ineffective and the transmission will be operating on a
much reduced level of protection. In hot weather these transmissions will whine
and rattle because of poor vibration dampening and
metal contact.


NAPA sells the GL4 but they may have to order it in for you. I know that the GL5 stuff does eat synchros and other softer metal parts...

 

A tractor or farm supply store should carry GL-4. I bought a gallon of it at a regular hardware store 4 or 5 years ago and have been working it down since.