You might try using "NoAlox" or "Penetrox" - or some other namebrand
compound between the tubes. It contains particles for 'cutting-through' the
aluminum oxide insulating film that would normally form - and - would
inhibit the oxidation of the aluminum. Its also a grease - encourages
smooth action. (put your gloves on.)
available at in the electrical depts at home centers like lowes - or at
electrical supply companies.