What's everyone using for clutch oil? We have L&T clutches and use L&T oil, but it seems like something a little thinner would work better. Back in my Horstman clutch days it seems like Horstman oil was thinner than L&T. L&T oil looks like plain old auto tranny fluid to me, but maybe it isn't. Thanks for your help!
"Plain old auto tranny fluid" is an interesting concept.
The principal function of this sort of oil is to transfer heat. Fluids do a much better job than air, but they can boil. I used to have an auto shop that worked on my Hondas, including my MDX which I use as my tow vehicle for my 7 by 12 enclosed kart trailer. On one hot day towing my trailer to Sacramento, my tranny fluid boiled and blew out of the tranny, coating the underside of my car and the front of my trailer, and the car would only barely move until I pulled over and let the whole mess cool off.
I looked into my owner's manual and saw that Honda was very emphatic that only Honda tranny fluid be used, since it was developed to have a much higher boiler point than "plain old tranny fluid". My shop patiently explained to me that it made no difference, since all tranny fluid was the same. I energetically lectured them at length and explained that their ignorance was actually dangerous. I moved on to another shop not long after that. The owner of the new shop was an auto enthusiast, and understood all about the differences in transmission fluid. That was over a decade ago.
So, clutch fluid. If you are a light weight driver you could probably try all sorts of fluids to see how they hook up. If you are a more substantial driver like myself, you might need to be more careful. On race days where I've had a couple of spins and recoveries during a single heat, I have managed to boil off a great deal of the oil with my extra starts from a dead stop - which is why I carefully check my clutch oil after every run.
A few thoughts for your consideration......
There was a thread about clutch oil not too long ago that you should be able to search out. It discussed the issue at length. The bottom line, at least in my mind, was that automotive ATF works just fine in most cases. That's what I always ran back in the day and it's what I continue to use.
As Jim pointed out, you have to keep an eye on the oil level and condition. If you overheat the oil it will carbonize and need to be changed. I never had an overheating problem with the Margay gearbox which has a large oil volume and that big aluminum housing that provides a huge heat sink. A chain drive engine clutch would certainly be more sensitive to heat.