One of the military units match conditioning Garands sprayed them down with WD40 prior to shipment to an area command for issue. The guy at the district supply center just about pooped his pants after opening the crates and seeing a thin film of rust on all 24 of those M1's metal parts. The guy at the unit that sprayed them got reprimanded.
The match conditioning unit would also take away anyone's Garand that had been lubed with Lubriplate, then instructed to only use Plastilube. If it happened the second time with that person, they would never be issued another Garand.
Best lube ever for Garands is called Plastilube; a brown medium thick grease. It's often available in surplus stores usually packaged in tiny plastic clear jars with a yellow cap on it. Or get it new:
Here's where it should be applied to M1's:
Bolt locking lugs, bolt bottom (very thin) where it slides over cartridges and follower, round part at the back end and the op rod lug and flats that ride in the receiver rails.
Stock ferrule where the lower band fits around it.
Op rod channel where it rubs the bottom of the barrel.
Op rod cutout where the bolt lug fits.
Op rod's front 5 inches or so with a very thin coat to make cleaning powder residue off easier.
Op rod spring as well as the inside of the op rod (small long wire [coat hangar wire?] with a loop at one end holding a cleaning patch coated with Plastilube).
Op rod's claw at its end where it fits on the follower parts.
Bottom of the barrel where the op rod rubs.
Trigger guard's locking lugs.
Receiver's rails where the bolt lugs rub.
Receiver's groove under its hump where the bolt rubs.
Receivers notches for the trigger guard's lugs.
Receiver's rear sight elevation knob side grooves.
Receiver's grooves where the follower guides ride up and down.
Rear sight's elevation slide and base groove.
Rear sight's knobs' threaded and areas bearing on the receiver.
Hammer's top groove where the bolt rides against it.
In other words, every place where there is metal to metal contact except the trigger sear and hammer engagement parts that must be dry.