Transmission Fluid = Creeping Death

[calvinhunt]

gmcjr,
  Yes, that chart does help.  It helps a lot.  The only thing is, now you've embarrassed me because when Carl sees this I'll be in trouble.  I just hate it when he's right.  (Just kidding.)  
  
  Seriously, though, this chart has caused me to do a Google study of viscosity classifications (in order to properly understand the chart).  I must admit that it's not the first time I assumed something to be a certain way just to find out it wasn't that way at all.  I remember my dad quoting an old German friend, "So soon vee get old. So late vee get smart."

  So, my conclusion will be, as I go though my Jeep preparation for this summer's drives, I will inspect the transmission gear oil for metalic flecks.  If there are any I will drain it and install straight mineral oil, most likely aviation 50 wt. non-detergent, uncompounded engine oil.

  I have saved the chart where it will be available for easy access in the future.  Thanks again, I really do appreciate the "education".

[garage gnome]

Well, I got lucky. I changed mine out today in fear of this issue. I had no brass in mine. Whatever I was using was either compatible with it or the parts used to rebuild mine were of better quality OR there is no brass left in it. �;D Looks like dirty gear oil to me.

[calvinhunt]

Nate,
  What gear oil were you running and how many miles are on it?

[garage gnome]

I have no idea what it is. We have a 10 gallon drum at our business's garage I use. It is for our rollback truck. I'd say there is a little over 5000 miles on it since I did my restoration. It has been in there for 5-6 years now.

[gmcjr]

gmcjr,
 ï¿½Yes, that chart does help. �It helps a lot. �The only thing is, now you've embarrassed me because when Carl sees this I'll be in trouble. �I just hate it when he's right. �(Just kidding.) �
 ï¿½
 ï¿½Seriously, though, this chart has caused me to do a Google study of viscosity classifications (in order to properly understand the chart). �I must admit that it's not the first time I assumed something to be a certain way just to find out it wasn't that way at all. �I remember my dad quoting an old German friend, "So soon vee get old. So late vee get smart."

 ï¿½So, my conclusion will be, as I go though my Jeep preparation for this summer's drives, I will inspect the transmission gear oil for metalic flecks. �If there are any I will drain it and install straight mineral oil, most likely aviation 50 wt. non-detergent, uncompounded engine oil.

 ï¿½I have saved the chart where it will be available for easy access in the future. �Thanks again, I really do appreciate the "education".

Glad I was able to help!!
This is what I use now, after seeing the error of my ways.

http://www.tractorsupply.com/en/store/travellerreg%3B-ford-tractor-all-mineral-90-transmission-fluid-2-gal
its cheap enough!!!!!

I knew about the yellow metal issue from working on tractors, but big dummy me didn't put two and two together on my jeep transmission until a couple months ago after reading about it on the 2a page. �

[Matto]

I changed tranny & T case today and it was dirty but not brassy. �I used the small pump in the picture below on a 1 gallon jug of the Nappa meneral oil. It took forever to fill the cases. Does anybody have a better method to pump the oil in?

(piming oil pump after engine rebuild, F134)

[Ryan_M]

I used this rig that I bought at NAPA a couple days ago. I still ended up with a fair amount of fluid in places it shouldn't be but it was much neater than the funnel method I tried last time around. It's pretty quick too. I think I'll also be able to use this pump to drain the tranny, which should cut down on the usual mess.

[Matto]

That looks like the ticket.  

[Carls_jeep]

Thanks gmcjr for posting the chart. I knew the 30 wt was on the low side of the 90-85 gear oil but since I have used it in my farm tractor for 11 years now working it very hard and no trouble I knew it would work in the Jeep.

My preference is a 40 or 50 wt engine oil but you could also use 100 or 150 ISO oil. Unless I have issues with shifting or something I will stay with the 30 wt non detergent engine oil. So far it shifts just fine now, we'll see how it goes in the summer.

[calvinhunt]

Thanks to everyone for all the collective research. �I know that for me it will be the straight mineral oil of one source or another. �gmcjr's chart gives a lot of direction and makes it easy whether we choose gear oil or engine oil.

One question still remains, why did so many of us run so long with the wrong gear oil that was etching our synchros and other yellow metal parts away. �People we look to for advice, like Carl Walck, should be in the know and they should be the first to advise us. �I'm not faulting Carl. �He has given me lots of good advise. �And he's not alone in the parts selling and advice giving business. �

At least, I do believe we have a solid answer to the problem. �I'm troubled about so many flat fender Jeepers that don't know this. �And what about the many friends who were once active members on this (and other) forums that don't know?

[Bob W]

Okay, I'm gonna poke the hornets nest here. First, I think the best oil for the T-90 is the type recommended in the service manual. In looking at the forums it seems to me that the "problem" transmissions are a minority of units with low mileage and that have been recently overhauled. Are the gold metal flakes caused by the oil or a mechanical problem? I agree that metal eating oil is not good for a transmission, but I think it will take many years before this will have any effect. Nate's example of the drum of gear lube is the perfect example. That's the lube almost every manual transmission and rear axle received from the 60s through the 80s. It was in every gas station and repair shop. Does it eat yellow metal? Probably, but how many transmissions actually failed because of it?

[garage gnome]

You know what, Bob is right. All these have been from recently overhauled transmissions. Mine was overhauled in the 90s. It makes 100% sense now why mine had no gold floating around. Something in the yellow metal parts must have changed between then and now (composition wise).

Oh well, I guess I didn't have to change it, but it was pretty yucky looking.

[gmcjr]

I reckon mines the other side of the spectrum, the transmission in my jeep has not been rebuilt since I've had it.(I'm gonna fathom a guess, by the way it shifts sometimes, that it hasn't been rebuilt as long as I've been on this earth. Btw, thats 30 years. The speedo currently shows 91,000 for what little that's worth.) I put gl5 in it a few years back, ran it probably 5,000 miles. I drained it a month or so ago when a similar thread was posted on the 2a page, the oil had a brassy tint.
I let some drain on my finger and then smeared it on a clean paper towel, there was brassy gleam (edited for better description) to it. It was enough to convince me. Your results may very.

[garage gnome]

I changed the gear oil in my '49 this past January. It had the original goopy stuff in it. I put the oil from our drum back in (after driving it around with #2 oil in everything to clean it out). I knew about this issue of the oil eating brass then, but I didn't really care about this tranny because it pops out of second. I'll be tearing into it when I fix the tub. It will be interesting to see if there is any brass in it or not. If not, I'll get the info on the oil I used.

[gmcjr]

That'll be interesting to see. I can't honestly say the brass I saw was just wear and tear, or result of chemical degrading. One the flip side, gl1 is cheaper. The Scottish in me likes that.