Transmission – differential – steering box lubrication

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    1931 Pierce arrow model 42

    What should be the viscosity of the oil in the transmission and differential ? 90 – 110 ?

    There is a greasing zert on the steering box. Should I use grease or oil and which one ?



    Arnold Romberg sent me a write up on the rear axle where he recommends using SAE 140 EP gear oil in the rear axle.

    The 140 has been in our rear axle for about 3 years now with no issues.


    The Ross steering box DOES NOT USE GREASE! It should have oil in it. The same goes for the Gemmer box also. Ed


    Hello Andre,

    Here is some good advice on lubrication from a past Message Board posting. The information below was originally from a posting from PAS Members Peter Williams and George Teebay.

    To quote George Teebay: Transmission & Rear End Oil: P-A [the company] only provided owners with the push-type heavy-liquid-dispensing grease gun, called, ‘compressor, grease’ in the owner’s manual. Because of the frequency of required lube, they assumed that much of the routine lubrication would be done by owners. That heavy liquid was ‘Special Compound,’ which was their proprietary name for 600W.

    I use 600W ONLY for the transmission and the steering box. (You should also use 600W for the Bowen auto-lube system.) I do NOT use the push-type gun for any of them–especially not for the steering box because you can still blow out seals with that. Heat a bottle in a pan of near-boiling water then pour using a small-aperture funnel. I’d prefer to use the 600W from a Model A Ford supplier for all 600W applications other than the transmission–but make sure you’re getting the dark, smelly, viscous 600W and not the clearer, thinner stuff some sell as 600W but which I think is just repackaged SAE 140.

    Differential: They did not have hypoid-style gear oils in 1928 (but they were close to it at that time), which is STRONGLY PREFERRED these days for the differential. As far as I know, SAE 140 hypoid-style gear oil is about as heavy as hypoid oil as we can find nowadays–but be sure to USE ONLY GL-4 rated, not synthetic (GL-6) or the now-common GL-5 which is for limited-slip diffs.

    Restoration Specialties, Escondido, CA (in the Parts and Services Directory)offers a line of sulfur free lubricants (so it won’t attack bronze) that can be used in your transmission, differential and steering box. They have different viscosities available, which can be helpful if you have a freewheeling Warner transmission in your 1931. There are large gears in these transmissions that like to keep spinning, that can make noiseless shifting more difficult. Heavier weight oil helps to dampen the movement a little, but you can’t go too heavy, or you will inhibit the lubrication of the freewheeling mechanism. I use a Lubriplate SAE 110 oil in my 1931 transmission.

    Following on to Peter’s advice, and I once saw Bob Jacobson use this idea, a plastic mustard bottle, with the tapered nozzle on it, is a dandy way to get lubricant into the steering box, especially if it is heated to temporarily reduce the viscosity like Peter advised.

    Instead of a grease zerk, it should be a threaded plug with a square head on the side of your steering box. Ed is absolutely right, “grease” does not belong in the steering box.

    Happy Motoring,

    Chris Diekman

    Happy Motoring,

    Chris Diekman


    Thank you all for your very informative answers.



    George: All this is well and good, except the ’36 and later cars have a pipe with a grease fitting at the end that is accessed under the left front wheel well. Using sae 600 or the modern thick steering grease available from Australia, the only way to get that in would be a high pressure pump type apparatus, unless you have another way to accomplish this.


    Tony, that’s a good point. Let me try to clarify.

    What Chris posted as sourced from Peter Williams and myself was written as info for Series 80/81 ONLY, although some of the info holds true for later cars.

    I do recommend using 600W in NON-synchromesh transmissions.

    For synchromesh transmissions and overdrives/free wheeling, I use 90 or 140 (depending on your climate and how worn your tranny is) that is GL-1 (i.e.,straight mineral oil without hypoid additives). In California, NAPA can get GL-1 oils within a day but those oils are not on the shelf–they do stock GL-4 and GL-5. Paul Johnson has posted good information on the desirability of GL-1, and the adverse effects of GL-5 (especially) and GL-4 in the past year or so.

    For 1929 and later steering boxes, I prefer GL-1 gear oil of a weight your steering box will hold, 90 if possible, heavier if necessary. For very leaky boxes, you may need to use the 800W or 1200W Penrite lubricants from restoration Supply.

    Re Tony’s issue: True, access to the steering box filler on 1936-38 cars is only by way of a fill tube. I don’t know whether the grease fitting he cites is authentic–my 1936 had a hinged-top oil cup at the fill end of that tube. I use a small pump-handle oil can filled with 90W gear oil to fill that tube. I agree that ANY kind of pressure filling of steering boxes is undesirable.

    One of the sources of confusion is, I believe, that in the 1920s 600W, a heavy gear oil, was frequently referred to as “liquid grease.” Indeed, that was the chassis grease dispensed by the “compressor, grease” to suspension fittings.


    May I suggest revisiting PASB 2011-1 for a discussion of rebuilding Ross steering gears. It discusses (p2-3) the Alemite zerk found on Late 36-thru 38 PA’s, that they were intended to oiled, and that Alemite currently markets a lever-operated oil gun for that purpose. Note that the Ross box is vented (p4-5), so oil can be pressure delivered to the box until it exudes from the vent hole. After installation of modern lip seals, the box operates on transmission weight oil without leaking.

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