I use nothing.
The control system needs to be ABSOLUTLY free with essentially no friction (can never achieve zero friction). The individual flying surfaces controls should fall under their own weight. I screen ball links and nylon hinges and reject (or fix) those with higher frictions. I take great care that there is no unintended slop anywhere. Some slop at the elevator horn is OK, but that is a completely different subject
A wet lube will attract dust and other debris into the moving joint over the life of the airplane. I believe a wet lube does more harm than good.
FWIW - the vibration associated w/ glow engines will tend to break up dry friction in the control system.
Jim Hoffman
Listen to Jim...He's absolutely right. Any wet lube on the bellcrank pivot or ball ends will attract dirt and eventually cause high friction, Any grease, especially something like white grease or chain lube will thicken more with lower temperature and cause very sticky operation.
Chain lube for motorcycles has polymers in it that deliberatly thicken and get sticky so the lube stays on the chain and doesn't get thrown off. This works for a motorcycle chain but definitely not in a low friction bearing like the bellcrank pivot. As Jim says...vibration is our friend here. Electrics may actually have a disadvantage here
![Hugh %^@](https://stunthanger.com/smf/Smileys/classic/icon_2.gif)
. Dry lube like graphite can be used but doesn't stay in the friction area very well and is of questionable value in an application like this.
Jim is an aerospace engineer with long experience in this area (as am I also).
Selection of components is key to free controls...if something is sticky or binding, fix it or chuck it, do not expect it to suddenly become better...it'll likely get worse.
Randy Cuberly