Gearbox and Diff oil grade - 1925-25X

[Buick Downunder]

Hi All

Can anyone tell me what the correct spec is for gearbox and diff oil for my 1925-25X. I use Penrite Transoil 140, which is what is recommended by the manufacturer specifically for this model. The tech info is:

TRANSOIL 140

Ideal as a rear axle oil in most Edwardian, vintage and pre war vehicles. While it can also be used as a gearbox oil, it may be too heavy in some applications. Does not contain any aggressive load carrying additives Do not use in axles fitted with any sort of hypoid gears.

Typical Data

Viscosity, Kinematic, cSt:

at 40 degrees Centigrade = 480

at 100 degrrees Centigrade = 32.4

Any help appreciated. Ben

[Mark Shaw]

Ben,

I have used both Shell Dentax and Texaco Thuban SAE 250 in my cars. Basically, this is the thickest lube commonly available in North America for industrial applications. It comes in 5 gallon pails and works well in both rear ends and transmissions.

It serves to slow down the transmission gears to help shorten the time between shifting (and also slows any leaks). I keep the transmission level about even with the bottom gear shaft in my transmissions and fill rear ends to cover the bottom 1/3 of what you would call the "crown gear". This lube will stick to the wetted gears and transfer quickly to the upper gears.

[Buick Downunder]

Thanks Mark

I thought this might be the case. I note that the manufacturer I use here provides SAE 90, 140 and 250 - as does the Shell Dentax range.

Using 140 will no doubt explain my crunching in neutral to first when idle, and also the continued axle leak LHS all over the wheel and brakes - even with a new seal!!!

I am going straight out to buy the SAE 250 today!

Ben

[Mark Shaw]

Ben,

To stop crunching into first, just don't shift into neutral when stopping. Push in the clutch to stop completely, then shift directly from second into first. Works great for me...

[dibarlaw]

Ben:

I have just secured the modern equivilent of "steam cylinder oil" the 600W

now is ISO VG 680 I am trying to secure more for some of the other car colectors locally. Particularlly for Model "A" Fords. I just asked the steam engine club where they got theirs. Hopefully this will solve my "crunching" in my 1925-25.

Larry

[Dwight Romberger]

Thanks Mark.

Great advice on shifting from second to first.

I never heard that one before.

Dwight

Edited January 6, 2012 by Dwight Romberger (see edit history)

[Buick Downunder]

Hi All

Just placed the Penrite Transoil 250 into the 25x last night and did a hasty highway test run in the dark - ! (as you do). Gearbox and diff changed.

This product is 250 SAE (equvilent to 600W Steam Cylinder Oil) and compared with the 140SAE which was in it, makes a very big difference to gearshift as others have suggested. Time will tell if the oil leaks from the axles stop now also. Thanks all for assistance.

Ben

[147 Franklin Airman]

On ‎06‎/‎01‎/‎2012 at 10:58 PM, Buick Downunder said:

Hi All

Just placed the Penrite Transoil 250 into the 25x last night and did a hasty highway test run in the dark - ! (as you do). Gearbox and diff changed.

This product is 250 SAE (equvilent to 600W Steam Cylinder Oil) and compared with the 140SAE which was in it, makes a very big difference to gearshift as others have suggested. Time will tell if the oil leaks from the axles stop now also. Thanks all for assistance.

Ben

Hi Ben

Just been reading your post about the 250 Penrite oil and was wondering how you got on with it in your diff? Have the leaks reduced? 

[C Carl]

I would be interested also. I stopped a significant pinion seal leak on a '73 Cadillac by going to 140 over previous 90. Now these REAL oldies , these slow old cars can also use semi fluid grease the in the diff. Or , blend up your heavier lube solution. Looks like Ben has not been here for 25 months. Any of you Southerners know him ?  - Carl

[Brian_Heil]

I use Snyder's M-533.  Snyders is a very large Model T /A supplier here in the states.  I asked for the specs.  It's Chevron Moropa. Good stuff with all the EP etc and heavy too.  And cheap.  It's on my front porch the next day when I order from them. I know this does you blokes in Australia  no good, sorry. I looked into a 5 gallon pail of Moropa but the shipping cost killed the deal.

[C Carl]

FYI , EP is superfluous and unnecessary in most diffs of this pre-hypoid period. Worm drives need EP also. Simple spiral bevel and skew spiral bevel gears do not have the sliding force component which requires EP.  - Carl

[147 Franklin Airman]

Just as an update, I have filled my diff with Penrite 250 and strangely it appears to be leaking more. I think a closer look at all/any seals is on the cards.

[Guest]

Generally speaking if you can put you little finger in the fill hole curl it down and feel oil you have enough.  Many if not most of the differentials out there are over filled and/or the vent is plugged, both of which cause leaks.  The same holds true for transmissions.

[147 Franklin Airman]

2 minutes ago, Tinindian said:

Generally speaking if you can put you little finger in the fill hole curl it down and feel oil you have enough.  Many if not most of the differentials out there are over filled and/or the vent is plugged, both of which cause leaks.  The same holds true for transmissions.

You have a point there, I guess most of us after knowing that it leaks a little would tend to overfill just to compensate for the leaks.

[Bloo]

Is there even a differential vent? If there isn't, and you have replaced leather seals with modern ones, you might need to add a vent.