I went to the link suggested and read it. Interesting comments. My favorite was the one who used a tiny bit of ATF, on safari but grease when "not in use". Not in use would not require anything, seems to me. Grease when you are USING the gun is what will prevent it from getting "gauld" (galled). I also believe it doesn't have to cost $17.95 per cc plus $9.95 shipping. Whatever grease you like or have at hand is fine, just keep it clean and fresh, as my first post suggested. Vaseline gets awfully thin in the hot Southwest summers. Better than nothing but it wouldn't be my first choice. Some prefer oil. Anything is better than nothing. Neither "attract" dirt and/or grit as is so often mis-stated in these threads.
