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Here's a link to ASTM tests run by Amsoil on 14 commonly available differential oils (mainly synthetic) in 2007- http://www.oilteksolutions.com/GearLubeWhitepaper.pdf (you may have to Google '' A Study of Automotive Gear Lubes".
If you're running bronze thrust washers in your diff, you'll want to check the D-130 test results for compatability with copper, Lucas and Royal Purple didn't fare too well...
I ran across a thread in BITOG where a gentleman had the bronze thrust washers in his rebuilt Triumph diff entirely disappear as a result of using a GL-5 oil after a few years. The fiber washers used elsewhere were unaffected. He rebuilt it in the mid 90's, I'm trying to get a line on what sort of Sulfur-Phosphorus EP additive that oil used (it was bright green after it dissolved the thrust washers).
"Buffered" Sulphur-Phosphorus additive protects surfaces by forming a black coating that wears off- it doesn't harm steel, but it takes thin layer of brass/bronze with it. Over time, the brass/bronze disappears. GL-5 has about twice the S/P that GL-4 does, so this process is more rapid. The idea with GL-4 was that the gearbox would be at the end of its normal service life before things like synchros became a problem. "Active" S/P additives were used before today's buffered compounds, they tended to form acids as they aged, which were bad news for brass/bronze and steel alike. Old-time gear oils used a lead-based EP additive which didn't harm brass/bronze, but lead EP went out in the 60's.
Temperature has an effect, the higher the diff oil temps, the more pronounced the effects are. Unfortunately, I haven't seen any correlation info yet that would allow you directly relate wear to temperature.
Given the cost of winch gears, I'd suggest you NOT pour GL-5 in there...
If you're running bronze thrust washers in your diff, you'll want to check the D-130 test results for compatability with copper, Lucas and Royal Purple didn't fare too well...
I ran across a thread in BITOG where a gentleman had the bronze thrust washers in his rebuilt Triumph diff entirely disappear as a result of using a GL-5 oil after a few years. The fiber washers used elsewhere were unaffected. He rebuilt it in the mid 90's, I'm trying to get a line on what sort of Sulfur-Phosphorus EP additive that oil used (it was bright green after it dissolved the thrust washers).
"Buffered" Sulphur-Phosphorus additive protects surfaces by forming a black coating that wears off- it doesn't harm steel, but it takes thin layer of brass/bronze with it. Over time, the brass/bronze disappears. GL-5 has about twice the S/P that GL-4 does, so this process is more rapid. The idea with GL-4 was that the gearbox would be at the end of its normal service life before things like synchros became a problem. "Active" S/P additives were used before today's buffered compounds, they tended to form acids as they aged, which were bad news for brass/bronze and steel alike. Old-time gear oils used a lead-based EP additive which didn't harm brass/bronze, but lead EP went out in the 60's.
Temperature has an effect, the higher the diff oil temps, the more pronounced the effects are. Unfortunately, I haven't seen any correlation info yet that would allow you directly relate wear to temperature.
Given the cost of winch gears, I'd suggest you NOT pour GL-5 in there...
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