My outdrive oil looks different than when I put it in. I have chhanged the outdrive oil several times watching for water, and I am not sure whether it has water in it or not. The oil is yellowish in color. The last time I changed it I used regular 80/90 in hopes that water intrusion would be easier to determine. It does not seem to seperate in the drain pan. Is it normal for the oil to develop the yellowish color? Can I use a 12volt DC air compressor to pressure test the drive, If so How many pounds should I let build in the drive, and for how long? Thanks