Recommended Fluids

what diff oil is recommended and how many ounces/quarts?

dana 44 w/ detroit locker
dana 30 w/ TrueTrac limited slip, worm gears
brake fluid, dot...?
manual trans sm465

 

I use 85w90 in axles, and trans. dot 5 for brakes (doesn't attract water or lift paint, but have to flush out system 1st)

 

..

 

85w90 in diffs with a friction modifer, 85w90 in trans as well DOT3 if you are not going to flush the brake system

 

Here's a good primer on brake fluids. http://www.stoptech.com/tech_info/wp_brakefluid_1a.shtml

I would suggest the heretical notion (in some circles) that you should change your brake fluid every few years. It's not hard if you have the system down (ie speed bleeders, an assistant to pump the pedal, whatever). Remove all the fluid in the reservoir (suction gun, mity-vac works well for this), add fresh fluid, bleed the brakes, top off, done.

My VW shop manual recommends replacing the brake fluid at intervals as part of routine maintenance. US shop manuals typically don't even address brake fluid life. My guess is that brake parts will last longer with fresh fluid. Certainly you'll maintain the boiling pointof the fluid (see link above).

 

Huh?

"Since water boils at 212 degrees Fahrenheit (100 degrees Celsius) the adsorbed water dramatically lowers the boiling point of the brake fluid. A minute amount of water suspended in the fluid decreases the boiling point as much as 1/3. Damn!

The fluid in the system absorbs water through the breathers, through the caliper piston seals and by magic. Not only does this reduce the boiling point, the entrained water leads to corrosion of both ferrous and Aluminum internal parts. Double Damn!! So buy your brake fluid in small containers and don’t save the leftovers.

...Unfortunately the hygroscopic nature of the ether based fluids means that they should be completely replaced at scheduled time based intervals (annually would be good) and that the system should be bled to replace the fluid in the calipers every time that it is overheated to the point of generating a soft pedal. Yes, the pedal will come back as soon as the fluid cools somewhat - but the boiling point is now reduced and the pedal will go mushy at a lower temperature the next time. Triple Damn!!!"

I presume that boiling the fluid degrades it somehow.

 

Oh, this ...

"Why the heck do we use brake fluids that absorb water in the first place?

Believe it or not, one of a brake fluid’s most vital characteristics is its ability to absorb water. Yes, you read that correctly – brake fluids absorb water by design and that is really a good thing.

What?

Whether we like it or not, water is everywhere and finds its way into everything. That’s just the nature of the beast. Even our brand-new sealed brake system will eventually absorb water given enough time.

The magic of diffusion allows moisture in the air to permeate microscopic pores in the rubber brake hoses, the nylon master cylinder reservoir, and the various rubber seals in the hydraulic system. Sadly, there is nothing we can do about it and if left unchecked the water would sit in our brake system and rot it away from the inside out.

Hence the need for brake fluid to absorb this unwanted house guest. Because brake fluid absorbs water into solution, the local concentration levels are typically low enough that corrosion is slowed dramatically. As an added benefit, when exposed to low temperatures, the solution state prevents the water from pooling and freezing on its own. While water in brake fluid will certainly increase the solution viscosity at low temperatures, this is much more desirable than having little chunks of ice plugging up the system!

So, the next time you are bleeding your brakes to remove the water-contaminated fluid, don’t curse at the automotive gods too loudly. After all, the fluid was only doing its job."

Yes, you don't want little drops of water in your brake fluid.

 

i forgot to mention the transfer case! dana 18... i can use the 85w90 as well?

and how many quarts will i need to fill both diffs, trans and trx case?

 

yes 85w90 will be fine in the d18. not sure on the exact amount you will need but 6 quarts should be close for everything (front & rear diffs transfer and transmission) thinking 2 quarts for each diff and approx 1&1/2 for transmission and another 1&1/2 for the transfer. heck buy 7 qts, its always handy to have a little extra for knuckle pudding

 

Damn, after reading this thread I thik I'll go change my brake fluid!

 

I think that you should change it with 85w90. I agree to some members. I used it too.