Holy cow man........... after reading all this and catching up.......... I went and checked my air filter. We drive on the beach quite a bit as well as drive in more nasty horrid places. Was dirty of course but nothing as bad as your describing, thank God!!! Maybe all those chickens I've been killing have been paying off and doing their job hahaha. Are you absolutely positive that the smoke is WHITE? Because what your describing is telling me that the smoke should be blue. If it's only doing it at high revs it can be tough to tell. I'd almost bet money that a bit of that sand that got in your carb ate up a valve seal and at hi revs your pulling oil in and burning it. When you checked your antifreeze level........did you open the rad or just check the overflow tank? Or both? Compression check is easy. Any shop should be able to do it. I would also ask for a leak down test. That will tell you if your rings are holding up as well as valve seals and head gasket. Leak down test will pressure up the chosen cylinder, then see how long it takes for the pressure to bleed off. With the radiator (rad) cap off.......... that will tell if the head gasket is bad. Add air to cylinder and watch for bubbles in the rad. I would do all these tests with the engine cold, then again warmed up to running temp. Like Trax said......... Black smoke is fuel Blue smoke is oil White smoke is water, break fluid, transmission fluid. Can only burn tranny fluid if the rig has an automatic not manual and can only burn break fluid if the rig has a vacuum booster for the breaks. But...... if you ever have a rig that's burning break fluid.............. the motor isn't long for life and will not be rebuildable.