As the title suggests, what weight gear lube are you pouring over your air lockers? I'm using synthetic 75/90, and I'm wondering if it's too light to keep the seal (in the locker, not one of the OE axle seals) in cooperative condition. I've had that oring replaced once, and I still find I need to roll for a few minutes to get it to stay locked, particularly fall-spring, although I'll also run into it cooler times of the day in summer. (Even with ~24 hr daylight, in July daybreak can get down to the 40s pretty easily, but then it can climb to 90 before the sun lowers itself a little.) Once the diff warms up, the compressor only cycles about every 30 minutes or more. Recommendations?

I run 75W250 Redline shockproof oil in mine... It is closer to 75W90 in terms of viscosity but has additives to make it thicker under high temp conditions. I also run my ARB air pressure at 55-70psi and it is working fine, locks and unlocks with ease.

80/90 Valvoline dino in mine, lock in the second I throw the switch.

I use 80/90 Valvoline in mine as well, with no engaging/seal problems either. Even after a night at sub freezing temps the locker works without fail. Almost everyone I wheel with runs ARB's, and none of us have had the problems you have had.

What type of air source are you using to engage it? To high of air pressure is an easy way to blow the o-ring.

It's the standard ARB compressor (not the newer compact). I haven't quite decided to part with my a/c yet. Heard that the ARB units are prone to blow at higher than the 90psi (iirc) required as a common complaint? I've only come across that they tend to burn up when used as a sole oba source to constantly do tires or keep a tank full. Might be time to have that ac refrigerant drained and get them regulated down 5 or 10 psi, but the front never gives me this trouble with their compressor and the same weight lube either. I did check the junctions with soapy water. They're all skookum.

it's the pressure switch actually that ships with the locker itself.

it's set to kick in at around 60 and stop when it hits 100psi.

buy a pressure switch that stops around 80psi.

I built my current set of ARB RD23s with 5.29s about 3 years ago. The truck is a daily driver/weekend wheeler. zero problems with my ARBs or gears so far.

I run 90W140 synthetic with a shot of B&G gear lube additive.

I don't think oil weight is going to affect your air seal. Brr that's cold.