We only use semi fluid grease in wheel bearings and I use it in the steering box of my old timers. We still use chassis lube on grease fittings and u joints. I think the new Spicer spl joints recommend semi fluid and a high pressure grease gun will pump it but we could not control it to where we didn't blow the seals of the u joint. I think the spl joints are assembled with semi fluid but I haven't talked to anyone who is able to grease them with it once they are assembled. Our trucks travel several miles of dirt road daily which is covered with gypsum dust which is acidic. We use a grease that is approved for dozers by Catapillar. I agree with you that there is no sense in trying to lube joints with semi fluid. Our joints run 500,000 miles and are usually replaced because a yoke gets loose on the spline and we don't even inspect the joint, just replace it. But for trailer bearings and steering axle bearings, I wouldn't think of anything but semi fluid. We used to pack bearings till we saw bearings in our sleep. Then came stemco oilers. They were a big improvement, but the seals didn't last long. We now have wheels that haven't had the hub off in 500,000 miles.