What do you think of using Automatic Transmission Fluid in the chaincase?
Why would you want to use ATF in the chaincase? I’m assuming you think ATF will provide enough lubrication for the chaincase with much less resistance, which will translate into less loss of horsepower. The logic is to reduce the rolling resistance of the vehicle, allowing more of the power produced by the engine to make it down to the track, minimizing the power loss due to friction. As the temperatures get colder, this would become more evident.
I don’t think ATF would provide adequate lubrication. I would be more interested in long term durability. My recommendation is to run a 100% synthetic chaincase lube. This will maintain superior lubrication, keep the components running cool, and will not turn into “tar” at extremely low temps. I’ve even known racers to remove all of the bearings from the drive line and rear suspension, clean out all of the petroleum based lubricant and re-pack them with a synthetic grease for less friction and loss of power.