Best modern replacement for 160 wt gear oil

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I am not a lubrication engineer, by any stretch of imagination, but have learned that a top of the line modern 15-40 synthetic motor oil is not a good substitute for the old 160 wt gear oil for some specified applications on our early Pierce-Arrow automobles. Is GL-1 a good substitute for 160 wt, especially with the properties to NOT damage brass or bronze materials? Those of you with experience or knowledge, please respond.

Al

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There are four basic types of gear sets used to transmit power across a 90 degree turn.  They are bevel, spiral bevel, hypoid and worm. My ’29 has the bevel type where each tooth is parallel to the axis of rotation. An improvement is the spiral bevel gear where both pinion and ring gear have some twist, but the axes of rotation intersect. The hypoid gear set is the most common one used today on rear wheel drive vehicles, first tested by Packard in 1926 and in common use about 1950.  There is enough twist in the gear tooth the pinion and axle axes do not intersect, allowing a lower hump in the floor.  All three of these have the ring gear with teeth on the side. The spiral element of spiral and hypoid sets allow higher loading and quieter operation as contact spreads across more than one tooth.

The final type of right-angle drive is the worm drive. The two largest differences are the ring gear has teeth on the periphery, so the drive shaft location is dictated by the diameter of the ring gear. The worm gear is usually steel and the ring gear is often bronze or other yellow metal.  Worm drives require special oils without sulfur or phosphorus to prevent corrosion and pitting.

Each of these types have a minimum grades of oils for proper operation. Even though our cars are not heavily loaded, use the proper oil. While it is OK to put a higher grade oil in any of them, do NOT  use a lower grade.

The GL -1 oil has no EP additives and is only good for the bevel gears (’29 & older and all transmissions), not for any having a sliding element tooth profile.

GL-4 or GL-5 both have EP (extreme pressure) additives for spiral bevel and hypoid gear sets, also fine for bevel gears. This agrees with my 1955 SAE handbook and Gleason 1951 gear design book.

 

 

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Generally GL5  gear oil has been considered too aggressive with its EP additives for older synchromesh manual transmissions with yellow metal,  and GL4 has been the recommendation. The GL5 extreme pressure additives adhere to the brass so strongly that it can tear microscopic bits of metal off leading to a kind of stress corrosion. Recently however some GL5’s have been modified and are now considered safe for yellow metal manual transmissions. Specifically Redline NS 85-140 is actually recommended for early synchromesh and I found it does improve the shifting. Except for that I would stick with GL4 140 weight.

140 weight GL4 should be hunky dory for hypoid rear ends.

Worm gear rear ends – I claim no knowledge! Changing gear oil always ends up being a messy smelly job! I get super cheap plastic oil transfer pump kits from Harbor Freight ($12?) and throw them away after because of the hopeless smelly slime all over them.

You can get super thick steering gear lube from Restoration Specialties.

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Alan,

The information given by Jim and Herb is right on. I am making the assumption you are inquiring for your ’31.

The 160 weight is an old designation, but it is still available.

For your transmission, you can use a 90, 140 or 250 weight.  I would start with a 140 (easily available) and see if you like the shift quality. If not try a 250 or 90 weight and see if it improves things. Changing the viscosity of the gear oil will change the timing of your shifts.

I would go with a GL-1 to be on the safe side just in case there is some yellow metal in it. Gl-4 is most likely OK (see below on checking for brass compatibility). Do not use a GL-5 unless it can be proven it is OK for yellow metals.

For the differential, you need an oil rated for Hypoid differentials (EP), like GL-4.  Most owners that I know of use a GL-4, 140 weight in the differential.

If you happen to acquire a 1933 8/1236 series car, use GL-1, they have a brass ring gear worm gear differential.  I have personal experience with a worm drive ring gear stripping because the wrong oil was used.

If you are concerned about a specific oil and its compatibility with yellow metals, get the Manufacturer’s Data Sheet for the oil and see if it contains information on the copper corrosivity test.  A 1A or 1B rating is OK with brass. As the ratings get higher, it gets more corrosive.

Thanks for the ride in Alturas, it was great visiting.

Dave

 

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