The standard lube for MGs is a light petroleum oil. Enough to float the breech block, the extractor and its little plunger, the right side wall, barrel extension and SOAK the belt feed slide. Each of these parts has critical movements or has a lot of resistence.
Keep a straight blade screwdriver handy to strip the round off the face of the breech block and to adjust the headspace. Remember to slip the belt feed lever to the left when closing the cover on a closed breech block.
(CLP is a light duty Cleaner Lubricant and Protective. The only part of CLP that will be working in a functioning belt fed MG is the carrier.)