Synthetic ATF and other observations

[Spook50]

Today I changed out all the fluids under my truck (tranny, tcase and diffs) and since I had finally tracked down a retailer here that sells Mobil synthetic ATF, I filled my tranny with that. Holy smokes what a difference. The fluid in there wasn't even a year old, and still looked and smelled clean, but shifting is worlds smoother and quicker with the synthetic. I didn't think it'd make a difference like that, just figured it'd help with longevity of the components, but it's amazing. I had thought my tranny was already in perfect shape, but now it feels even better.

Get this stuff if you can source it. I had to buy it by the case (at 45 bucks after tax per 6-quart case) so I went ahead and bought two cases so I've got some in reserve for when I'm able to install my hydroboost setup.

In other news, the oil that came out of my front diff was GROSS. Nearly black, and it had originally started life about two years ago as bright yellow Lucas oil, which is the only gear oil I use. I took a close look at the magnet on the drain plug and didn't see any shavings or chunks at all, just the typical grey/black gum (and no more than I would've expected either). Any thoughts on it the oil could've become contaminated at some pont, or if there's probably a bearing going bad somewhere, or even (worst case) something else is up and it's about to grenade on me? I don't often use 4WD aside from wheeling about once a month and when it snows, so it hasn't seen much abuse. This is making me think that it got contaminated somehow. Thoughts?

 

[Waggoner5]

I would guess that given the miles on the diffs, the housings probably have lots of grime build up inside. Everytime you change fluids, it washes the housings out and turns the fluids black. There is probably some wear up there also adding to the fluid color. Is the front axle original, with no rebuilds?

 

[lovetoski]

In other news, the oil that came out of my front diff was GROSS. Nearly black...Thoughts?

Since there are no metal bits in the magnetic drain plug, that's an indicator that bearings/etc are OK. No guarantee, but a good sign. Front diff should last a long time anyway since they aren't used much.

Most likely reason for the contamination is that inner axle seal has failed, allowing knuckle grease and diff oil to mix together. This is common on older trucks. Try dipping a long zip-tie into the knuckle (through the square plug on the top). If what you get has any characturistics of grease mixed with oil, then you have a knuckle rebuild in the future.

Or, as previously posted, it could just be accumulated gunk from inside the axle housing...

 

[Spook50]

Since there are no metal bits in the magnetic drain plug, that's an indicator that bearings/etc are OK. No guarantee, but a good sign. Front diff should last a long time anyway since they aren't used much.

Most likely reason for the contamination is that inner axle seal has failed, allowing knuckle grease and diff oil to mix together. This is common on older trucks. Try dipping a long zip-tie into the knuckle (through the square plug on the top). If what you get has any characturistics of grease mixed with oil, then you have a knuckle rebuild in the future.

Or, as previously posted, it could just be accumulated gunk from inside the axle housing...

Well I've already got everything I need for the rebuild and plan to do it within the next month, so it looks like I called that one when I ordered the parts
Even got a set of the DBA 4000s from Boston Mangler that he never installed. I'm hoping that I can do the rebuild and get the new rotors on the same time I do the rear disc conversion, so it'll be all new brakes front and rear.

Waggoner5, yep. Matter of fact I think the knuckles have only been done once in the truck's 216K miles.

 

[Darryl W]

Synthetic ATF is not hard to source. Contact me off list at dwormsley@mac.com and I can get you all you want. It works great I use it in my 80 and my wife's car.
Darryl

 

[yournamehere]

I changed my trans and xfer in the 60 with redline synthetic gear oil and thought I was driving a new truck. All hail the synthetics.

 

[Spook50]

I changed my trans and xfer in the 60 with redline synthetic gear oil and thought I was driving a new truck. All hail the synthetics.

I used to use Mobil synthetic gear oil in my tcase and diffs, but because of its dark color, I couldn't tell if there were any contaminates when I drained it, so I went with Lucas because it's probably the best dino gear oil you can get ,and it has a light color when it's new.