Transmission oil

[preaction]

Whats currently seen as the best option for transmission oil for a 47 with its factory trans, would the transfer case use the same oil ? Matt I talked to you about this a couple weeks ago but Im only remembering what not to use which is synthetic for the 47 non synchronized 4 speed.

[Matthew Welcher PWA]

What I would suggest is just normal 80w90 gear oil. It should work just fine for you. Good to see you on here. Have a great day and enjoy your Power Wagon.

[Ellion]

The normal 80w90 oil seems still the best option out there.

[53Crusher]

After much research, I became convinced that I should only run GL-4 rated gear oil in my truck. It would seem that GL-5 & GL4/5 can harm yellow metal in older vehicles. I run it in my transmission, transfer case and both axles. This was one of the few gear oils I could find that is GL-4 rated only. https://www.amazon.com/Sta-Lube-SL24.../dp/B000M8RYMC

[W_A_Watson_II]

I run the Lucas Synthetic 50 wt. Trans Lubricant in my NP435 and in my brothers Stock M37 Trans.

Common gear oils are mostly base stocks with little more than an addition of sulfur and phosphorus as a total anti-wear package. We at Lucas Oil Products consider this inadequate. Most heavy duty truck transmission manufacturers now consider sulfur and phosphorus to be potentially corrosive to copper and brass and consequently recommend against common gear oils for this reason. The other 50 WT we have tested, synthetic or otherwise, are pure base stock, we consider this also inadequate.

Lucas Synthetic 50 WT contains an exclusive additive concentrate derived from synthetic oil that ensures lower operating temperatures and better lubrication, especially to upper bearings and gears. This is a long lasting fluid that is far superior to conventional synthetic fluids and contains nothing that could be harmful.

Meets or exceeds API MT-1, Eaton Transmission Div., 164 rev 7, Mack Truck TO-A Plus, International Truck TMS 6816 and other applications requiring non-EP Lubricants.

[Matt Wilson]

Here's a link to a thread in which Amsoil engine oil (yes, engine oil) is recommended by Tim Kingsbury for all manual transmissions, with a claim of great success. Tim seems to have a LOT of experience with vintage mopars from the 30's through 60's, so it's worth giving it a thought.

[Matthew Welcher PWA]

These are all very interesting thoughts, the amsoil 15w40 to me is a great idea but? Would it be much to thin depending on outside temperature?
Also Crusher, do you have any of the GL4 related research you would care to share?
I have spoke with will and am going to try the Lucas in the 435 of my W200.
what other things have you guys physically tried as other gear oils or oil itself in the drivetrain?

[53Crusher]

I am certainly not a chemist, but the concept of phosphorous and sulfur harming yellow metal made sense to me. It's still relatively easy to find a GL-4 gear oil. You can pick conventional or synthetic and in a variety of brands and weights. I just didn't want to risk a GL-5 causing corrosion of brass and other soft metals in my truck. This is the article I found to be helpful in my search. I can't attach the PDF as it is bigger than 125kb but here is a link to the site. http://www.widman.biz/uploads/Transaxle_oil.pdf

Paper also discusses the fact that motor oil viscosity charts are different from gear oil viscosity charts. A SAE 40 motor oil has approximately the same viscosity as one of the thinner SAE 90 gear oils, while the SAE 50 Motor oil is similar in viscosity to the thicker SAE 90 gear oils.

[Matthew Welcher PWA]

Thank you Tim, I will give that a good read.
the Viscosity comparison from gear oil to engine oil is very interesting. Hope all is good out west this morning.

[Desoto61]

I know Charles Talbert was using 50wt Royal Purple race oil in his transfer cases because of this after his discussions with RP engineers. I like Charles' work a lot and so did the same after I rebuilt my t-case. I'm a big fan of synthetic lubricants in gear boxes and such, I think it's overkill for most engines unless you are going to extend the change interval or run it really hard, but use it in everything else I care about.

[Dutch]

I was amazed at the difference Mobil 1 Delvac transmission 50 made. Night and day difference to valvoline 80-90 gear oil I was using. Shifts sooooo much nicer and quieter. Like I said, could not believe the difference it made.

https://www.zoro.com/mobil-mobil-del...08/i/G3165267/

[preaction]

Dutch, have you seen any evidence of the trans leaking any more with the Delvac in there ?

[Dutch]

No, I have not. I had a small leak before I switched and have not noticed any increase in the amount of oil that leaks from the one seal and no new leaks have come from switch either. Like I said though, huge difference in gear noise and how smooth it shifts. I never thought oil itself could make that big a change.

I also change the transfer case oil at the same time. It made my truck much more quiet and pleasurable to drive.

a link to my first post on this oil- https://powerwagonadvertiser.com/for...ansmission-oil