Just learned the hard way to not use Royal Purple.
Oh? please, do tell. I hope nothing bad has happened.
I've been following this thread with interest as I'm considering a different trans lube as well. I am currently using Castrol 80w-90, but have considered synthetic such as Royal Purple.
Put it in my car last Saturday. Drained the oil the trans PO had in it. Don't know it WAS but it was very thick. My car (got it last August) has been bone dry as far as leaks. The engine rebuild has less than a thousand miles, and during the rebuild the PO cracked the transmission, determined it needed no rebuild. So he cleaned it all up and put it back together. Like the engine, less than 1000 since he inspected and cleaned it.
Ran it 100 miles or so on Sunday. Shifted nicely, drove well. Encouraged.
It has been parked in the garage since Sunday. Since then when coming home I'd look under the car for any sign of leak. Bone dry all week, until getting home from work last nigh to find a tablespoon sized puddle of royal blue under the car. Underside of trans along the seam had a thin film.
I've read that this has been a problem, the thinking is the synthetic is dissolving the sludge that prevents the Dino oil from leaking at a spot already weak...a failing seal or an infant leak.
But the car didn't have enough miles in it since the rebuild to warrant any sludge, and what I drained looked clean. I drained the RP last night, and it was clean, no dislodged sludge.