i had to drain the synth oil in my chaincase so i could split it and look inside. dont have any left. could i throw 80w-90 gear oil in my case? wont be for too long. will stop by local dealer tomorrow to get more chaincase oil. sled is a 1992 polaris indy 500 classic (with reverse)
ATF is closer to the consistency of chaincase fluid. Gear oil has greater shear strength which is needed in gear-to-gear contact. A chaincase has a chain and two sprockets. There isn't a requirement for high shear strength in the lubrication. What is necessary is a thinner oil to permeate into the links of the chain for better lubrication.
In the absense of the correct lube, I would run ATF before gear oil. That said, you hardly ever hear of anyone having issues with a chaincase as long as they run something in there!
2007 Dragon RMK 700 155", 2008 RMK 600 155", 95 Prowler 550 2-up, Really OLD AC Cheetah
ATF can be corrosive to metals and certain rubber seals. The transmissions that use it are designed for its properties. Chain cases are more similar to differentials with 75w-90.
But I agree with BC_DAN. It really doesn't matter. If you run vegatable cooking oil, you will get the exact same life as someone with $$$ factory oil. (as long as the ATF doesn't eat your seals and leak out at least, that would be the * in the story.)