Written by Dallas Frohrib, owner of CherryBalmz Weapons Lubricants.  I’m not advocating any particular product, and don’t use CherryBalmz, but there’s some excellent info here.

“For those who don't yet know me, I own CherryBalmz Weapons Lubricants - we've been engineering gun lubes for about 6 years now. Those who do know me, know I enjoy sharing the universal science of gun lubes in general, and don't just shill for our products.  

In another gun group, I was just asked about the broad differences between greases and oils for guns - it's something you all might appreciate, no matter what your current lube is.  

Here's the basics:

Greases are classed as sealing lubricants, while oils are classed as flow lubricants.

Unsealed machines get greases, while machines with lubricant support systems, like gaskets, pumps, filters, and reservoirs, generally get oils - because the oils are designed to transport friction contaminant away from friction surfaces.

When you remove those lubricant support systems, the machine is now unsealed, and oils will flow right out of those friction surfaces, with just gravity and motion alone. The machine will get only a tiny fraction of the cycling it would have otherwise had, before you need to jump in and fix things - in effect, serving as the lubricant support system yourself.

Greases act like a sealant - they stay put, and keep friction contaminant away from your friction surfaces. That sealant effect also applies to the grease components themselves - upper layers of the grease trap air and oxidative elements away from the lower layers of the grease, keeping it fresh and reliable for years on a machine. Junk may build up on the exterior of the grease, like a crust even in cars and major machinery exposed to the elements, but the friction surfaces and lower layers of grease are fresh, clean, and protected.

The biggest misconceptions about grease are that it's basically "sticky peanut butter", and that it will clog up in guns. And for the NLGI #2 greases that are virtually all anyone sees, this is largely true - it's just way too thick for optimal reliability in guns. But greases come as light as cooking oil (NLGI #000) and as thick as a block of clay (NLGI #6). Our firearms greases, being optimized for gun energies and gun realities, are all lightweight, the heaviest being about like a creamy mayonnaise, around NLGI #0.

Because of all of these factors, you could have pure unicorn tears as an oil, but it will still flow away, and pick up and suspend friction contaminant, often migrating it right into your friction surfaces. A properly weighted grease will stay put, and seal junk out. The difference in performance for total round count between gun oils and our greases is about 10x. Most ARs need to be re-oiled every 250-350 rounds, depending on the oil (some will do more, usually thicker ones like Lucas or 20w50 motorcycle oil), while our Black Rifle Balm typically gives about 3000-5000 rounds on one application. And it stays wet and reliable for over 3 years on a gun.

If you want to use oils, for a number of reasons, go with thicker oils in spring, summer, and fall, then switch to a lighter oil, like ATF or 0w20 in winter. If you want to use grease, look for the lightest you can find. Besides ours, Geissele's is great, and lubriplate offers an NLGI 00 that's pretty good. I don't want to sound salesy, and won't get into what makes ours different here, but you'll be safe with any of these greases.

Just remember, the question with any gun lube isn't, "Will it lube?", but, "How well will it lube, for how long, and under what circumstances?" The issue is understanding a given lube's limitations - know those, and you'll be safe.

That said, here's a "grease vs oil" application guide you might find in any plant maintenance handbook, or Tribology 101 textbook - take a look and see what column better describes the realties of guns:”

This is something that I feel like should be straightforward and not subject to debate among the community, but I've heard so much bs and differing opinions on cleaning and lubing since I got into shooting. Thanks for sharing.

Grease on parts that rub others and oil on non contact surfaces as rust prevention and help to keep clean.

I drink the Cherrybalmz Koolaid. It is pretty damn amazing. Dallas is also extremely knowledgeable and produces/sells a great product.

Cherrybalmz all the things

Yes. Cherrybalmz is good stuff.

I tired all sorts of lubes and greases when i was younger, now i just use whatever motor oil i have at the house for my firearms.

the only difference i have found is that the lighter weight oils seem to be a little better at keeping carbon buildup in check, suppressed or not.

I use oil on everything but I'm not killing my guns... they get shot a few hundred rounds and cleaned.

You did however inspire me to use some grease on the Sig P229 which I know you are intimately familiar with.  Speaking of, what is your/agency protocol on your Sigs?

been on the Cherrybalmz train too.

I once went probabably 1500 suppressed/steel case on CB until one day my bolt wouldn't pull back. Mortared it, squirted some ALG ultra thin grease on it, shot the night, then cleaned later.

cherry balmz is good stuff.  

With the cherry balmz, I no longer need to spray some more oil in the action during a range day.

That is a really good article and after 40 years of working on different types of machines from lawnmowers, guns, to tractors and large aircraft; Using the correct lube is very important. The second part of the equation is the environment you are operating in can have an effect on the type of lube required. Dirty dusty areas can cause dirt to stick to grease. also tight tolerances may not work with thick grease. I took and AR15 Armorer course with Sully from SLR15. he recommended a synthetic oil Since they work better in cold weather. like zero or below, since he is from Minn. Most of us can clean our rifle every range day and don't use them daily in a dirty environment. So if you clean it after every range session and don't bet your life on it you can use any left over auto oil.
I haven't tried the cherry balmz but I think I will, Right now I have a supply of Slp2000 EWL that has worked perfectly in many AR platform guns.