I have an $8 one pound can of Mobile 1 Synthetic Wheel Bearing grease that I've been using on my semi-auto rails for years with no problems and still have 7/8 of the can left. The synthetic doesn't attract dust as bad and stays in place for a long time.
I was using Rem-Oil w/ Teflon on the actions until I ran out and tried the wife's Singer Sewing Machine All Purpose Machine Oil for under $3 for four ounces. Works perfectly.
"We must reject the idea that every time a law's broken, society is guilty rather than the lawbreaker. It is time to restore the American precept that each individual is accountable for his actions." - Ronald Reagan