Going to try a very lightweight oil such as WD-40 and see where this goes. to the cost.
Please, not WD40. While it is thin, it has a bad rating as a lubricant. Just about any regular oil is better. If it's ok with the belt - and being oil has to introduce doubts, 3 in 1 with PTFE is a reasonable thin oil and unlike WD40, has good staying power.
The WD part of WD40 means water displacement, and it does it by attracting water to the stuff. You spray something wet that shouldn't be, and it removes the water by attracting the water to itself and the mixture then falling away with the excess. While it does this quite well, the object then needs oiling with a proper oil as any residual WD40 will carry on attracting moisture and is a poor lubricant. WD40 does have uses in the workshop, but far fewer than their hype would have you believe.
Discounting any that think WD40 is the answer, (if you live in the desert and spray often it might be) what do the Harley Davidson crowd dress their belts with?