Rear main seal leaking

[imikec]

There's a product called Bar's Rear Main Seal Repair. Has anyone ever used it, and did it work good?

[logic]

These products that stop oil leaks, work on the principle that they cause rubber to swell, therefore tightening the seal at the main bearing,
I would regard this as a temporary measure, I think the last time I read up on it, it was ok for 10,000 miles, not a lot nowadays,
You don't state what car you want it for, but if it is like mine, ( Pajero,) you would be better leaving it alone, if the leak isn't too bad, as the rear end of the crank can wear slightly oval
Either way, get expert advice on this.