I changed the gear oil on my engine prior to testing (report on Boating activities and destinations) the oil which came out was thick black, no water or metal, I changed it to Mercury all purpose gear oil recommended by local chandler, after the change the big differance was the ease by which the prop could be turned by hand, I tested boat in water for 40 odd minutes and now wonder if I should have used some type of thick oil same as was taken out, is this Mercury oil suitable for this engine as I get the impression that prop is turning to easliy, may just be warm weather thinning oil or what? any advise please as I wouldn't like to wreck the gearbox, thank you. JBD
