I'd grab a junker and tear one down if I were you. You can certainly wipe a layer on the outer tube but the whole idea is to lube the ball screw assy. inside. Once you rip one apart and look at the guts you'll get it.I did 6 pumps and cycled the actuator but I don't see any grease on the shaft. So, I emptied a 3 oz tube of grease into both actuators and still no evidence of grease on the shaft. The grease tubes were empty when done so the grease must have gone into the actuator tube.
Almost certain that if you took a friction comparison with the motor off before and after you will see it is reduced a lot.
Can't really say I've ever needed a whole tube of goo to get things working smooth and slick.
Look out for squish-out definitely.
*oops....a 3oz tube. i was thinking a regular tube for a mans grease gun. lol! three trigger pulls from a smurf gun is like 1 from mine.*
Good Job. Keep us posted.