I just put a new clutch in my '86 Ranger, because look at the old one: It needed a new flywheel, and I replaced the rear main seal while I was at it. As usual, I discarded all of the instructions and installed the seal like normal, with a light film of grease so it doesn't get torn up while driving it in. After I got the transmission bolted back up, I found a little piece of paper on the floor from FelPro. It said something like, "PTFE seal, do not lubricate, must be installed dry, I'm a FelPro seal, look at how special I am, PTFE 4LYFE, blah blah blah, etc." This is the first time I've seen an oil seal that wants to be installed dry. So, how long will my greased seal last before it shreds into a million pieces and starts spraying oil everywhere? Oh btw, I will be filling it with Maxlife 10W-40 and servicing the PCV valve, etc.