You dont need any so called high tech gun grease. Any wheel bearing grease is overkill for the Garand.
IMO the M1 Garand Collectors Club is a much better deal than the GCA. If you join the GCA its $25 and your memebership is only good for 4 months as their membership runs Sept-Sept no matter when you join
http://www.m1collectorsclub.com/
The M1 Collectors Club is $14 and runs for a full year from the day you join. No quasrterly magazine but a good cheap way of fullfilling Club Membership. Just like the GCA they will forward Club Membership details directly to CMP or you can join one of the CMP stores