Is lubriplate ok for the op rod and should the gas valve be dry
Lubriplate is just fine. I personally use Mobile 1 synthetic grease (red stuff). Here's some info in general on grease in regards to the M1.
This is important. The Mil spec for rifle grease
ONLY deals with washout. It doesn't deal with thermal breakdown, how effective a lubricant it is.
With that in mind. Take a look at the Mobil 1 grease I use.
If you look at the rating for the Mobil 1 grease to the washout test. ASTMD1264, only 6% of the grease was lost during the test @ 175F !!!.
You will never ever operated your Garand in an environment that will wash off the grease. Unless someone tossed you in a boiling pot of water with high pressure sprayers. Even then some of the grease will still be there.
Quoting an airforce research lab
ASTM D 1264, known as water washout, was modified to
include synthetic sea water. While there are various lubricant bearing tests for corrosion, none measures a lubricant’s resistance to sea water. It is expected to combine corrosion and washout
measurements in this test. For many military applications, this property may be helpful in determining the life of the component, as the ability of the grease to remain in place will insure sufficient lubrication as well as corrosion protection
The actual test is the following.
1. An ABEC 6204 bearing is packed with four grams of grease.
2. The bearing is spun at 600 RPM and either 100F or 175F water is sprayed onto the bearing at a rate of 300 ml per minute.
3. The percent of grease lost is the rating number.
The more important rating has to do with wear. That test is ASTM D 2266.
The ONLY spec for rifle grease in regards to the M1 is MIL-G-46003. There are several other's out there for new weapon systems.
That spec is
Grease, Rifle MILG-46003 Used as a lubricant for rifles and other small arms, when such weapons are used under conditions of sustained rain.
Water Spray Test: The water spray test is an accelerated test
to determine the effect of a heavy rainfall on the performance of the weapon. The test consists of a spray of water falling at a rate of approximately 0.4 inch per minute or 24 +/- 3 inches per hour. The spray of water is directed over the entire weapon by means of a special shower head positioned about 3 feet above the weapon. The water and air temperatures are measured and recorded. The test weapon is lubricated with MIL-G-46003(MR) grease before the test but not between the test phases.
The TEST procedure follows. Take any grease and subject it to the following test and if it passes.. You have a Mil-G-46003 rated grease!
The Automatic fire sections can be omitted.
We've already shown that the Mobil 1 synthetic grease has superb washdown characteristics. Why would the grease fail this spec in a heavy rain? If spraying HOT sea water on it doesn't cause failure? It wouldn't. So Mobile 1 grease meets or exceeds the Mil Spec for grease used on the M1.
Please keep in mind that you will never find yourself in a situation where you need this level of grease protection. I'm pretty certain I'm not going to be neck deep in a swamp during a 175F monsoon with driving salt water rain and an M1 anytime soon.
The second part of your question. Grease or oil in the gas cylinder is in no way harmful to the rifle. Oil blows out within a few shots and grease leaves a nice film behind that makes cleaning up super easy and super quick.
The M1 Gas cylinder is a very loose system, the pressure in the gas cylinder has decayed to zero before the op-rod moves 1/2 inch. From that point on it's just coasting back.
Eric