Surveyor Shelby, I will try to answer all of your questions. First we are talking degrees as measured with a protractor, not percent. Second I called Cummins engine when I first had this problem and talked to an engineer, who said the engine is only certified to operate up to 17 degrees nose down. Third, after 17 degrees the engine pumps oil out the vent tube , so no matter where the other end of the tube is , you don't have enough oil in the engine, my oil pressure dropped to zero the first time this happened to me , I quickly shut it down. The next thing I did was move the vent to the valve cover, I drilled a 3/4 inch hole in the drivers side on the third buldge back from the front, And found out why Cummins doesn't put it there, Puting a clear pepsi bottle on the vent tube , I drove 60 miles and had 2 teaspoons of oil in the bottle, too much oil to throw overboard. So I bought a Walker Airsep and installed it. For the Walker Airsep you have to use a vent hole in the valve cover, plug the original hole with a short piece of hose with a wooden dowell inside, with 2 hose clamps on it. After installing the Airsep on the turbo you have to cut a 1/2 inch strip off the airhose, but try it first and maybe omit this step. The oil is drained back into the crankcase where the turbo oil draines back, they give you a fitting to combine the two. When you push the airhose on the Airsep it hits the back of the Alternator, and you first have to move a fitting on the back of the alternator, no big deal, The first time you do this It is really hard to get the airhose on, and you have to make sure the bottom of the airhose is on the airsep, however after a few days the hose takes this shape and it isn't near as hard to take off or put on. The hose will be about 1/3 deformed where it hits the alternator , but I talked to W. A. and they said it doesn't hurt performance ( I know ,they sell them) but I haven't noticed any differance. Yes there is an oil film on the turbo blades, and probably in the intercooler. Did you know Cummins install's the W. A. on their Marine engines as standard equipment? So maybe the oil in the intercooler doesn't hurt anything. As far as replacing the filter , I would just wash it out with a degreaser once in a while, the filter I think is fiberglass . Any more Questions?