Preamble:
In 1992 I bought a '57 Chevy pickup which had been off the road for many, many years. I serviced the original trans with fresh gear lube before the truck went back on the road and drove it all over Montana and even on an 8hr trip to Nebraska for many years without troubles. Driving the truck with a relatively heavy trailer across country one December the trans input shaft started to leak. This transmission has no input shaft seal by design, only an oil slinger. Multiple attempts at fixing the leak resulted in multiple failures. New bearings, new slinger, larger drain hole in the case, shielded front bearing, even adjusting the fill level lower have not cured the issue. I've tried different weight oils including 75W, 90w, and multi-viscosity. It's currently using 140 wt gear oil. This is not a small leak. Its soaked two clutches so they cannot hold the full torque the engine produces. I have plans to replace the trans with a modern design 5 speed and as I only drive it a few hundred miles a year I have lived with the leak knowing a change is approaching. I suspect this problem is related to a difference between gear oil in '57 and gear oil today since the trans should be in exactly the same condition if not better than when designed.
Current situation:
I now have a 1936 Plymouth which I intend to start driving. I hope to take it on a 150 mile trip in July. Like the '57, it has no front seal, only an oil slinger. This car has old oil in the trans as it's been stored since '59. I'd like to add to or replace the trans fluid but I'm not too excited at the thought of soaking the clutch and underside with gear oil if this one starts to leak. In my '36 Plymouth manual I noticed this statement: "For certain purposes such as decreasing the tendency for lubricant to leak from the case, small amounts of soap or other materials are sometimes added by manufacturers of lubricants."
Question:
Is old gear oil likely to have ingredients not needed in commercially available oil today? Is there an additive which could provide the same effect? Is there an oil which is likely to contain these additives? I'm used to searching for mechanical parts that aren't available for this car, but finding chemistry that has been left behind might be tougher.
Note: Maybe adding bar and chain oil to the gear oil would be sufficient? That stuff barely pours out of a jug when temp is below 60 deg, it clings to everything, and it's loaded with extreme pressure lubricant.
In 1992 I bought a '57 Chevy pickup which had been off the road for many, many years. I serviced the original trans with fresh gear lube before the truck went back on the road and drove it all over Montana and even on an 8hr trip to Nebraska for many years without troubles. Driving the truck with a relatively heavy trailer across country one December the trans input shaft started to leak. This transmission has no input shaft seal by design, only an oil slinger. Multiple attempts at fixing the leak resulted in multiple failures. New bearings, new slinger, larger drain hole in the case, shielded front bearing, even adjusting the fill level lower have not cured the issue. I've tried different weight oils including 75W, 90w, and multi-viscosity. It's currently using 140 wt gear oil. This is not a small leak. Its soaked two clutches so they cannot hold the full torque the engine produces. I have plans to replace the trans with a modern design 5 speed and as I only drive it a few hundred miles a year I have lived with the leak knowing a change is approaching. I suspect this problem is related to a difference between gear oil in '57 and gear oil today since the trans should be in exactly the same condition if not better than when designed.
Current situation:
I now have a 1936 Plymouth which I intend to start driving. I hope to take it on a 150 mile trip in July. Like the '57, it has no front seal, only an oil slinger. This car has old oil in the trans as it's been stored since '59. I'd like to add to or replace the trans fluid but I'm not too excited at the thought of soaking the clutch and underside with gear oil if this one starts to leak. In my '36 Plymouth manual I noticed this statement: "For certain purposes such as decreasing the tendency for lubricant to leak from the case, small amounts of soap or other materials are sometimes added by manufacturers of lubricants."
Question:
Is old gear oil likely to have ingredients not needed in commercially available oil today? Is there an additive which could provide the same effect? Is there an oil which is likely to contain these additives? I'm used to searching for mechanical parts that aren't available for this car, but finding chemistry that has been left behind might be tougher.
Note: Maybe adding bar and chain oil to the gear oil would be sufficient? That stuff barely pours out of a jug when temp is below 60 deg, it clings to everything, and it's loaded with extreme pressure lubricant.
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