I would personally use some Copper Grease for this job as it would provide greater protection than vaseline.
Copper grease is NOT water proof.
And if gotten into the innards of those adjusters, will probably cause wear from the copper particles.
John, you really need either a tin of nickel anti-seize grease, or a tube of thick silicone grease (an NLGI grade 3 should be perfect) - either or both are available from
www.Cromwell.co.uk 
