the grease on o-rings in motors is only to lubricate the o-rings during motor assembly. The grease has no effect or affect on how well the o-ring seals. People have used skin oils, Petroleum Jelly, and various common and exotic greases. As someone mentioned, AT supplies SuperLube with new motors but recommend Petroleum Jelly when the supplied amount runs out.
In AT motors, the sealing is done by compression when the end caps are screwed down. The o-rings need to be lubricated so they slide between compressing surfaces without damaging the o-ring while closing the end caps. In snap-ring, CTI and many other cases, the sealing is radially by squeezing the ring between the case and the nozzle/end cap. In these motors the lube is to allow easy assembly of the motor without damaging the o-ring when it is slid down the case.
In both types, the lubricant becomes irrelevant once the motor is assembled because it has already done the job its there for.
My personal experience is the Petroleum Jelly works perfectly fine in AT motors. I use PJ in motors up to L size. I would probably still be using it in CTI and Snap ring motors to M if I hadn't gotten tired of it turning liquid in the summer and making a huge mess. I switch to SuperLube because it doesn't melt in the summer sun, not because it works any better on o-rings.