I have recently had an issue with the rubber seal under the dash of my 2013 Softail Standard leaking and stuffing the paint on the left side of the tank. I was told that it was a combination of the plate being over tightened during manufacturing and the recent hot weather. Then on Saturday I went for a ride on my 1979 Shovelhead Lowrider and after filling the tanks I had petrol suddenly leak out of the cap. On checking under the cap I found that the rubber seal under cap was stretched and no longer sealing. I had a spare cap at home so I changed the rubbers over, with the new rubber a nice tight fit. Today when I took the cap off I found that the new rubber was now loose. On checking the old rubber I found that it had shrunk back to its normal size. I have recently changed from BP Premium 95 to BP Ultimate 98 petrol and was wondering if anyone else has had any issues with their tanks leaking.

Thiis is the first I've heard of the problem.  Sorry that I can't provide an answer for it.

Used the BP 98 for a few years now without issues.

I've had no problems and generally use Ultimate when I can.

So are you suggesting that the different spec fuel may have damaged the seal of your petrol cap/s?!

E85 Ethanol kills Rubber Seals and Standard Fuel Lines,,, I would say the Service Station your getting you Fuel from is mixing in E85

Another happy BP Ultimate user here. 50,000km mainly from 4 different BP servos

Thanks everyone for replying. I have used the BP 95 for years without a problem and won't have thought changing to the Ultimate 98 would have caused any trouble but like walka suggested, I am thinking that the Ultimate 98 may be an ethanol mix, either by mistake or as a cost saving measure.

No issue, with BP 98, but owned a shovel from new, think stock fuel cap used cork, but don't give me a hard time if i'm wrong.  & think the rubber seals u got are aftermarket i had trouble with them too long b4 bp 98. also my shovel still runing strong , mate owns it & still rides interstate when he can .