Big Question: do you want the oil to lubricate, or also protect against corrosion?
This may give all you who want to try or use or discount using Syn. Motor Oil for lubing and protecting guns some answers and something to think about. Has some long reads but also has some answers by the scientific community regarding the use of oil.
Not a bad read, but also a very good reminder why "GlockTalk" can be such a waste of time - so many children shouting at each other rudely, interspersed with really intelligent comments. The "noise" factor is so extremely high! But that conversation is all about lubrication and not corrosion protection. And I think many of us confuse the two issues when talking about what we want as a "gun oil."
That conversation re-iterated much of what is said here - guns are not "special animals" that need crazily specific lubes. However, it in no way addressed the main beef with motor oil - great lube, poor corrosion protection. Also, it was a very one-sided debate between two people with
some technical knowledge but not specialists. One of them was a knowledgeable amateur, and the other an non-doctoral
organic chemist, and not a petroleum or inorganic chemist. There is a BIG difference - trust me. Furthermore, that particular poster has been a member there only a short while, and his post count put about 20% of his total posts in that one thread. And half of those posts were spent shouting down and being rude to other respected posters. Not a definitive statement, but again not a ringing endorsement of that poster as a fountain of wisdom.
The point those two glossed over, and I hear over and over again, is that the open-air oxidation properties of motor oil is extremely weak, synthetic or "dino." As a lifelong and avid amateur mechanic (my father was a professional machinist and motor mechanic and trained me at home), motor oil was always about the most useless thing to smear on an exposed bare metal surface to give it some corrosion protection. It would be rusted the next time it was breathed on heavily. Any "gear head" (or as they say on
Top Gear, "petrol head") knows this.
I am not basing my judgment solely on this, but on the fact
professionals say the same thing. When personal experience and professional advice coincide, it's usually worth paying attention to. Now I can understand Glock guys loving motor oil: Guns made out of non-rusting Nylon 66 (another interesting revelation of that thread), tennifer coated, and with very little metal to try to protect. Quality lube is the ticket; corrosion protection is riding the short bus.
On my steel guns, I'll stick to lubricants with just as good lubricating abilities but with more proven anti-corrosion properties. On plastic guns, motor oil sounds fine to me. If I own one handgun, and lube it weekly, then motor oil might work fine. But if I clean and lube one of my guns each week, that means it's a year before I get around to that gun again. So on my non-carry guns or recently shot guns, I need a lubricant I can trust to lube AND provide corrosion protection in the PNW for a year. Motor oil ain't it. It'll do in a pinch. Heck, in a pinch I'd use Crisco. But as a long-term lubricant/protectant, no.
Here's a good, non technical primer on gun lubricants from a highly respected gunsmith, not a petroleum engineer:
http://grantcunningham.com/lubricants101.html
