this_is_greg Posted June 9, 2018 Share Posted June 9, 2018 What oil is recommended for the rear-end on my 1938 Dodge RC half ton pickup? The manual states "Powerful Extreme Pressure Gear Lubricants design specifically for Hypoid Gear Lubrication ....SAE No. 90." Will modern 90w gear lube be ok this is old truck? Thanks in advance. Greg Link to comment Share on other sites More sharing options...
Alan Cutler Posted June 9, 2018 Share Posted June 9, 2018 Gear shop that rebuilt mine gave me two quarts of Lucas Oil Gear 80w 90... Link to comment Share on other sites More sharing options...
this_is_greg Posted June 9, 2018 Author Share Posted June 9, 2018 Thanks Alan. Mine hasn't been rebuilt. It appears someone welded the two halves together. Not sure why someone would do that. Maybe thought that's how you stopped a leak??? Link to comment Share on other sites More sharing options...
Alan Cutler Posted June 10, 2018 Share Posted June 10, 2018 very odd....I’ve seen old gasket material swell up and look like it was welding metal, but once I pryed them apart it was clear it was swollen material. Link to comment Share on other sites More sharing options...
Spinneyhill Posted June 10, 2018 Share Posted June 10, 2018 Maybe RTV or similar oozing out and not welds? 14 hours ago, this_is_greg said: Will modern 90w gear lube be ok this is old truck Please don't use that 90w slang. In oil speak, the W means something, basically behaviour when cold (think "winter"). If you want SAE 90 oil, say so. It will, of course, be much thinner when hot than when cold. The SAE 90W-140 behaves as SAE 90 when cold and 140 when hot. 80W-90 likewise. I think you can go ahead and use 80W-90 (EP) as @Surf City '38 has said. Link to comment Share on other sites More sharing options...
Grimy Posted June 10, 2018 Share Posted June 10, 2018 You should use SAE 90 GL-4 EP (extreme pressure) gear oil, available at O'Reilly's and other chain stores. These days the shelves are full of GL-5, which is for limited-slip, so be sure you get GL-4, which is much easier on any yellow-metal (e.g., brass, bronze) components that may be in the diff. If the diff is loose/worn, use 140 weight or mix half-and-half with the same brand's 90. Link to comment Share on other sites More sharing options...
this_is_greg Posted June 10, 2018 Author Share Posted June 10, 2018 I haven't gotten underneath for a close look, just stuck the camera under it to snap a photo of the drip. This is what I found. Link to comment Share on other sites More sharing options...
Reg Evans Posted June 10, 2018 Share Posted June 10, 2018 Yup, looks welded to me......That's Crazy Link to comment Share on other sites More sharing options...
John Dunn Posted June 12, 2018 Share Posted June 12, 2018 Was just looking through an OEM Late 30s dodge passenger car shop manual and saw rear axle lube recommendation of 160 weight for summer and 90 weight for winter as required. That's 80 year old info based on the lubricants of the day. I really doubt anyone ever changed their axle lube twice a year. I'm going to put some modern 90 weight in mine and call it good! Link to comment Share on other sites More sharing options...
JFranklin Posted June 12, 2018 Share Posted June 12, 2018 12 minutes ago, John Dunn said: Was just looking through an OEM Late 30s dodge passenger car shop manual and saw rear axle lube recommendation of 160 weight for summer and 90 weight for winter as required. That's 80 year old info based on the lubricants of the day. I really doubt anyone ever changed their axle lube twice a year. I'm going to put some modern 90 weight in mine and call it good! Since you will probably put more miles on it during non-freezing weather You should go with 140 gl-4 gear lube 1 Link to comment Share on other sites More sharing options...
John Dunn Posted June 12, 2018 Share Posted June 12, 2018 That makes good sense. Definitely not for cold weather use any more. There is a shaky looking old heater in the cab and I'm not even hooking up the hoses. Link to comment Share on other sites More sharing options...
Guest Posted June 12, 2018 Share Posted June 12, 2018 (edited) SOP used to be to drain a pint out of the differential and a 1/2 pint out of the transmission and top both up with coal oil/kerosene. Then in the spring you drained both and put 140 or 160 back in. In my personal experience at minus 40 degrees F if the unit is parked outside and there is a wind, the engine will start but the transmission and differential are solid. After the engine is warmed up I could leave the transmission in neutral (always parked in neutral in the winter) and slip the clutch a bit to get the input shaft spinning. Once the transmission was warmed up then you could drive away but usually had to stay in first for a mile or two. Did this twice and then added coal oil and never had to do it again. The coldest I drove the car in was minus 54 F and had no troubles. Edited June 12, 2018 by Guest (see edit history) Link to comment Share on other sites More sharing options...
C Carl Posted June 13, 2018 Share Posted June 13, 2018 4 hours ago, JFranklin said: Since you will probably put more miles on it during non-freezing weather You should go with 140 gl-4 gear lube Yes , Greg and John. Hypoid gears shear the oil down. I have gone to 140 to stop a pinion seal leak on a disposable beater. Dried the old thing right out even with thousands of miles of subsequent use. - Carl Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now