Best lubrication for transmission ?
 

What is the best lubrication when changing the fluid in the transmission and also the rear differential ? I am wondering if I should stay with 600 weight oil or use something better. THANK YOU.

Re: Best lubrication for transmission ?
 

I would stay with 600W.

Re: Best lubrication for transmission ?
 

Unless you have a Mitchell transmission, Stay with 600W. But it isn't 600 weight oil.

Re: Best lubrication for transmission ?
 

I suppose for both gears 600-er industry machine oil that is slightly additized.

In addition MoS2 comes in the gear box, which is good if sometimes you shift noisily (teeth scratching).

Re: Best lubrication for transmission ?
 

Some like the 600w (which is about 240W) and that not a bad idea. You probably won't go wrong with it. However, some of the workable and working concoctions being used out there with good results are as follows, 100% STP, Certain "Steam Cylinder Oils", Lucas Hub oil, and others! All will work to some degree. I can't verify this, but I have heard that at least one vendor mixes his oils 50-50 with STP. When you're choosing an oil, it not only must lubricate the gears, but it must slow down the gears to allow shifting and it must stay in the trans case and not leak out.
Terry

Re: Best lubrication for transmission ?
 

We have been using 50/50 mix of STP and 600w oil from Mac’s.

The last bottle of 600w oil that we received from Mac’s looked and felt like STP.

Re: Best lubrication for transmission ?
 

Thank you all for your replies . I appreciate all suggestions. Thank you

Re: Best lubrication for transmission ?
 

Dose anybody use an EP oil in the diff? I see no reason why a modern EP (extreme Pressure) oil souldn't be used. It is lighter viscosity and will do a better job. If the sorts of oil referred to above work, I think a 85 or 90 grade GL4 or GL5 would be more than OK.
Comments other than the usual "If Henry did it that way, I'll do it that way"? If EP oils were available to Henry, he'd have used them, I'm sure so why shouldn't we? I understand that the thicker oil in the gearbox makes changing down easier but there are no such considerations for the diff.

Re: Best lubrication for transmission ?
 

I think the 600W, 140wgt or 250 wgt will work just fine.

Re: Best lubrication for transmission ?
 

100 percent STP.

Yeah - I know. It's not a lubricant.

Funny. It seems to think it is.

Joe K

Re: Best lubrication for transmission ?
 

You really do not want a lighter viscosity, the 600 or it's equal works fine. Part of having a thicker lube it as was said above is for shifting the straight cut teeth on the gears, it kinda slows them down. That being said, you can put what ever OIL in your box that you want, it's yours to mess with. 2ed, straight cut gears require different lube then the newer helix cut gears boxes and trying to compare them is apples and oranges.

Re: Best lubrication for transmission ?
 

I'll put it this way, STP does a good job of not being a lubricant. Steam cylinder oil got us through the first 60 years just fine. Other concoctions might suffice. Look at it this way, pretty soon no one will be able to get steam cylinder oil, right. You will have missed a chance to know. Those steam guys are probably cornering the market as we speak. Washtay.

Re: Best lubrication for transmission ?
 

I use Mobile 600 XP Extreme pressure oil designed for heavily loaded spur and helical gears. It’s equivalent to SAE 140. Used in the tranny and diffy. No gear grinding with a slight hesitation when shifting or when double clutching.

Re: Best lubrication for transmission ?
 

https://www.redlineoil.com/80w250-gl-5-gear-oil-2

80W250 GL-5 GEAR OIL
Recommended for SAE 250 or where SAE 140 does not provide adequate protection
Alternative to Red Line Heavy Shockproof® in problem Nitro Drag Race Vehicles
Can be used in Model A, Model T vehicles and Antique/Classic cars calling for 600W
Reduces noise levels in Morgan 3 Wheeler bevel boxes
Excellent for off road use where SAE 250 is required

API GL-5 is an engineering standard,API stands for american petroleum institute.SAE for society of automotive engineers.API GL-5 standard:
Gear Oil GL-5 delivers value through: ... The sulfur-phosphorus extreme pressure additive technology used in Gear Oil GL-5 provides good thermal and oxidation stability. In addition, this lubricant is fortified with rust and corrosion inhibitors, a foam inhibitor, and a pour point depressant.


Use a 250w in trans,85/90 GL-5 is fine for the rear axle.

Re: Best lubrication for transmission ?
 

Exactly what I was proposing.

Re: Best lubrication for transmission ?
 

I'd be a little concerned that too-thin lubricant would work its way past the seals. I don't think they're intended for light oil.

Re: Best lubrication for transmission ?
 

I have a can of 600W from back in the 30's. It is much blacker and viscous than the current 600W from suppliers. I tried to use some, but it was almost impossible to dispense into a differential. It resembled the crap I have to clean out when I rebuild a differential.

Re: Best lubrication for transmission ?
 

The 600w the vendors sell doesnt have an API or an SAE rating,hard to tell what your buying.The model A rear axle uses the same components and tolerances as a modern rear axle,the 85/90 GL-5 spec meets the demand.

SAE 250wt (600w) is used to help slow the spur gears down to meshing speed in the A transmission.A high compression head increases shift speed by allowing the engine to rev up and down quicker,I've yet to experiment with 85/90 GL5 with the high compression head I use,but I imagine the difference will be negligible..GL 5's higher pressure means it stands the load of meshing gears without wiping off the surface negating the weight advantage of the 600w. .

Re: Best lubrication for transmission ?
 

The transmission is one thing while the rear end is another! What works in the transmission may not work well in the rear end. Frsintance, the rear gears are in constant mesh and don't have shifting issues. So why can't we use a lighter oil and reduce some of the internal resistance. I frequently notice that model A owners will use the same lubricant in both the transmission and differential. I'm not saying this is wrong, but you're dealing with two different mechanical systems with different needs.
Terry

Re: Best lubrication for transmission ?
 

Lubricants other than GL-1 are not recommended for transmissions with yellow metal bearings. The sulphur is detrimental to the copper in the yellow metal (Brass, bronze). Fortunately, there are no yellow metals in a model A trans or rear end. BUT there are Bronze bushings in the steering boxes.
Terry