Bob Barrows recommends this product for lubricating the aluminum threads (not o-rings) of your Bearhawk gas caps.
Bob says this lubricant lasts longer than anything else he has tried over the years. Lube your o-rings with engine oil or bearing grease every few times you fuel your Bearhawk or Patrol.

EZ Turn is a specialty lubricant/sealant used for fuel and oil line valves & is resistant to high temps. Especially effective where high octane fuels and aromatics are present. EZ Turn is also extremely efficient as a gasket paste & anti- seize agent. EZ Turn will not gum, crack or dry out. Each shipment is independently tested. Excellent for tapered plug valves, aircraft engine manufacturing, and marine applications. EZ Turn is the functional equivalent of fuel lube.
EZ TURN (FUELLUBE) 5 OZ TUBE
Aircraft Spruce pn. 09-00306 $11.85