Gear oil

[FORD*DIEHARD]

Saw Valvoline has a Synpower Sae 75w-90 Full synthetic and a full synthetic without synpower, which is better to use or which brand do you recommend?

Researching fluid capacities, this is what I found for 1974;
Front Dana 44- (3.5 pints)
Rear 9" - (9 pints)
Transfer case - (2.75 pints)
Manual trans - (4 pints)
Total of roughly (20 pints)

Correct me if I am wrong, sounds like the best way to do this is to buy a couple (1 gallon) containers and a couple (1 qt) containers and to fill up the (1 qt) containers with the (1 gallon) containers because the (qt) container is designed to fill ?

Thank you in advance for your time/help,

Sonny

 

[Broncobowsher]

Oh boy, another internet oil thread!

It's clean fresh oil, beyond that it is whatever makes you feel happy. These gear boxes are simple designs that work well with simple oil technology from 50-70 years ago. The worst new oil you find today is better then the best oil from back in the day. And these parts lasted for 50 years without issues on that old oil. They are still good. Any new oil will be fine.

There is also a gear oil pump. Looks like a high volume hand soap pump. Put the hose in the hole and start pumping. Stop when it gets to the threads at the bottom of the hole.

No matter how well you plan you will either have left over oil or not enough oil.

 

[Slednut10]

This^^^^
This is the pump I use. Beats trying to squeeze it out of a quart bottle. Same as a pump for an outboard lower end except this one fits a gallon bottle.

 

[AC932]

Just a note though, if you're going gear oil make sure you're using a GL-4 gear oil, as it's designed to not destroy the yellow metals in the tranny. It probably won't actually matter, but it makes me feel better. I used sta-lube 85w-90 for the sole reason that the napa near me carries it in gallons, use basically whatever oil/brand makes you warm and fuzzy inside.

 

[72_EB]

Cheapest 80W-90 Non-Synthetic GL5 in diffs. Tractor Supply is good for this in midwest.
Don't forget friction modifier additive if you have a stock limited slip.

 

[Broncobowsher]

Some gear oil will already have the friction modifier added. It will say so on the label. It may be less expensive to buy the more expensive gear oil, thus avoiding having to buy the modifier.

 

[johnbeck]

I used Valvoline 50 racing oil. I'm told it has the same viscosity as 80/90 gear oil. Since I was having my C4 rebuilt I had the trans guy replace the seals in my Dana 20. The D 20 didn't drip oil before new seals but leaks at a seal and a bolt. Could the racing oil penetrate better than the gear oil and be the cause of the drips, or just sloppy workmanship of the tranny guy? Get me a price on the quart, no, gallon container of 80/90 you find. I love the smell of gear oil... John B

 

[Timmy390]

Just a note though, if you're going gear oil make sure you're using a GL-4 gear oil, as it's designed to not destroy the yellow metals in the tranny. It probably won't actually matter, but it makes me feel better. I used sta-lube 85w-90 for the sole reason that the napa near me carries it in gallons, use basically whatever oil/brand makes you warm and fuzzy inside.

Same...I use sta-lube 85w-90

I get mine off RockAuo...Cheaper than local NAPA

Tim

 

[johnbeck]

I was kidding about the gallon for the leaks. Fortunately it leaks only enough to stain the driveway and make a mess.