Light synthetic grease is usually better than oil on frame rails of any handgun, IMHO. This is especially true if dealing with pitted surfaces.
One really good light synthetic grease that I like and use on my handguns is SuperLube. Here's an Amazon link to it if anyone is interested. $8.50 in a 3 oz tube or $18 in a 14 oz can. The link is for the can.
https://www.amazon.com/Super-Lube-41...05&sr=8-1&th=1