I am sure that the seatbelt jamming problem can be made smaller with a tiny amount of lubricant. They probably could do with a bit of lubing anyway. Don't use too much as excess oil will stain the clothes or seats. And don't expect it to eliminate the jamming problem.


With such heavy loads, I would expect the stress bearing parts of the locking mechanism to carve grooves and scars into each other, creating an interlocking set of grooves. They may also be bent microscopically out of shape (not anywhere near the point of breaking). Anyway, "keep it greasy and it'll slide easy". Anything stuck with lube present would be 10 times more stuck without lube...


Caveat: I don't know if manufacturers has put in any long lasting grease in the seat belt locking mechanism, such as grafitti (used in locks, btw). If there is, say, grafitti present, adding new oil will create a mess (oil flushing out the grafitti). And from that point you need to oil / grease regulary.