I had a Department Armorer warn me about using anything but straight gun oil on guns kept loaded (service firearms), and he put it like this:I understand the concern about penetrating oils and primers. Really, I do. However, over the last several years I've become convinced that the oils we gunnies like to call "straight gun oils" simply don't exist. It simply doesn't make sense to formulate oils for the tiny, miniscule market that is the gun oil market. From my very limited research, what we buy are common industrial lubricants, repackaged into small one-ounce bottles and sold to us at a premium. A quick look at the label on my gun oil and a walk through an automotive supply store convinced me that "straight gun oil" is simply packaged for our convenience. Even Break-Free CLP is easily purchased in one-gallon jugs, and I've seen it in the past in five-gallon cans.
I don't believe that the guys at Exxon-Mobil, or BP, or Phillips, even know that we exist. If one of their research guys came to them and said "Hey, we need to refine some gun oil!", they'd look at him like he was crazy, unless he could convince them that they could sell it by the tanker load. No, what we buy as "gun oil" is simply repackaged bulk lubricant, with extra hype and cool labeling.
Do I use "straight gun oil"? Yeah, I've got a few tiny bottles on the shelf because they're convenient. I also use 3-in-1 oil because it's convenient. I also use white lithium grease. The 2-ox tube I bought five years ago is just about gone and the next time I'm in Auto-Zone, it's time to pick up another tube.
I get it about primers and penetrating oil, but I don't believe that "straight gun oil" exists. It's a figment of the marketers imagination. And a highly profitable figment for those willing to package it. They can repackage industrial lubricant in one ounce bottles and sell it to us for over $100.00 per gallon. It's a heck of a deal for them.