These oil/grease threads border on the ridiculous. Generally speaking, all motor oils are approximately the "same" thing and perform "approximately" the same. The question is what is the range of same and approximately. Frankly, all substances with lubricating properties are going to work to some extent in non-full-auto firearms because those firearms do not really put any lubricant to task and push the limits of lubrication. The grease off my nose can probably sufficiently lube moving parts in a handgun for a while.
Espousing the idea that various lubricants are essentially equivalents merely because they share the same ingredients is somewhat silly. Just because your grandma made pasta gravy with tomato sauce, oregano, basil leaves, and garlic, doesn't mean that it is going to taste the same or have the same consistency as my grandma's using those same ingredients. They may both be edible and assist pasta to slide down your gullet, but the similarities may very well end there. These arguments vastly oversimplify the chemical engineering and formulation that goes into these products, particularly with regard to intended usage.
Furthermore, a number of these arguments have rather fallacious reasoning when it comes to retail pricing by, for instance, ignoring the power of economies of scale when it comes to material procurement, production, packaging, marketing, distribution, and so forth. The fallacious assumption is that CLP costs 10x Mobil 1, ergo I must be overpaying. That may, or may not, be true. You are certainly "overpaying" for gun lubricant if you use Mobil 1, because much of the cost in Mobil 1 comes from the additive package that is needed for automotive use. In other words, you are paying for "more" oil than you can make use of in a firearm application, or in other terms, Mobil 1 should be considerably cheaper if formulated for firearm use without all of the automotive requirements. Then again, such a formulated Mobil 1 might actually cost the consumer considerably more because the firearm lube market is considerably smaller.
Countzero, you could have just used cosmoline to store your firearm. It's not extreme pressure, (then again, why you would need EP grease for any handgun application is beyond me), but it's been used for decades and decades as a rust preventative for storing guns and naked metal surfaces (e.g. engine cylinder walls). After a time, the grease soaks into the surface of the material, hence the need for more "extreme" cleaning techniques on surplus firearms when you really want all of the grease off.
Heck, if you really like automotive products and carbon removal, then you should be using tranny fluid like Dexron III. It will keep your gun much cleaner than motor oil, and for long term storage, I guarantee you that no rust will present itself on any metal submerged in ATF.