The Various Values of Viscosity...

[Doogie]

Could a synthetic high-end/high grade motor oil (Castrol Racing Oils, Amsoil 20W-50 Racing Oil, etc) be used to lubricate the moving parts of an M4 subjected to a high round-count tactical carbine course? - the logic being that the stresses and temps a high-performance vehicle engine endures would translate (to a degree) to efficient lubrication of said BGC (etc.) over an extended shooting session(s). Would it create gun cleaning/maintenence issues not fully appreciated here?

[Heavy Metal]

Could a synthetic high-end/high grade motor oil (Castrol Racing Oils, Amsoil 20W-50 Racing Oil, etc) be used to lubricate the moving parts of an M4 subjected to a high round-count tactical carbine course? - the logic being that the stresses and temps a high-performance vehicle engine endures would translate (to a degree) to efficient lubrication of said BGC (etc.) over an extended shooting session(s). Would it create gun cleaning/maintenence issues not fully appreciated here?

The problem is you are comparing lube desigend for a closed pressure lubricated system to a system that is none of these.

[LOKNLOD]

Plenty of folks use motor oil for gun lube. I hear Mobil 1 mentioned a lot, for whatever reason.

[Joe_Friday]

I use Castrol Synthetic in my LMT. No problems, stays wet without gumming up (for lack of a better phrase) and it does not have a strong odor when it heats up. There is a very large thread on here somewhere that discusses using motor oil for lube and there are a surprising number of people that do use it.

[Dave L.]

I use Quaker State "Q", the 4X4 version. It works awesome and I also bought some needle oil bottles from Brownells.

[bkb0000]

i switched to mobil 1 last year after using conventional motor oil for a couple years.. i've done 600 round sessions with Wolf with zero malfunctions without relubing once, and still cleaned with relative ease. best lube i've used.

[tweakmeister]

I've used several viscosities of oils and prefer something on the "heavier" side of motor oils...10w30 or higher. The 5 and 0 weight stuff was like lubing with water.

[Ando]

Stick with 10 weight and higher, the lighter oils have a much higher volatility and are driven off with high heat.

[trinydex]

http://www.thehighroad.org/showthread.php?t=339348

http://www.thehighroad.org/showthread.php?p=4509221

i found these two threads a while ago. there seems to be pretty good scientific discussion there, with some cited materials. make your own decision, but be warned some will scoff at you for thinking you can use something that belongs in an engine, on a gun. also know that motor oil is a lubricant only, not a cleaner, not a rust inhibitor.

[Thomas M-4]

Mobil 1 synthetic 5w-20w same oil that I use for in my truck.
Brownells action lube plus on slide rails

[lanceriley]

I use 20w50w

[Ring]

ever try STP Oil Treatment, its thick like honey, good in hot weather, dont use in cold
http://www.stp.com/oil_oiltreat.html

[maestro]

Mobil 1 15W-50