Need gear oil recommendation for this car. Has anyone made the switch to synthetic in something this old. Currently has the old 90 weight stinky gear lube.
1954 Plymouth Savoy rear diff
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Anything would be better than the stuff that's in there, Redline and Amsoil are regarded as making excellent gear-oil alongside Schaeffers who are also very well respected.
I've been using Amsoil Severe Gear 75W-90 lube in my Studebaker differentials with excellent results. I suspect that an 80W-90 GL 5 gear lube from Valvoline, Pennzoil, Castrol etc. will be far superior to what was originally used in 1954.
I own both a 1951 Plymouth Cambridge & a 1949 Dodge 3/4 ton pickup. Both have the OE flathead 6 engines & stock drivetrains and both are in great condition. I am a big believer in synthetics...in fact I use Mobil-1 in both engines. BUT, in the transmissions and rear differentials, I use any good non-synthetic. The three brands listed in the post immediately above this one would be plenty good. Mine both have 75W-90, either Castrol or Pennzoil in the rears. I've got some old SAE 50 Pennzoil motor oil in the Plymouth's transmission...probably not the best. Of the current available for the 3-speed, the GL4 or GL4/5 gear oil would likely be correct.
MolaKule
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Unless the diffys have had modern seals installed, I would use a GL-5 80-90 grade mineral oil.
Hi,
I endorse wholly MolaKule's recommendation. Sulfur additive based older lubricants build up a residue that once removed certainly can cause seal seepage/leakage - this is typically attributed to a change to a synthetic lubricant
I endorse wholly MolaKule's recommendation. Sulfur additive based older lubricants build up a residue that once removed certainly can cause seal seepage/leakage - this is typically attributed to a change to a synthetic lubricant
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Modern 80w90 GL-5 is still going to smell bad. Gear oil needs a high sulfur content to protect hypoid gears.
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