Food Grade Lubricant Retail Sources (DC Metro)?

I recently obtained half my son's kegging equipment including 4 Corny kegs. I am in the process of testing the CO2 and pushing sanitizer through the new taps for my keggerator. I have a leak through the top of the corny keg and I've seen the instructions on moving the top around to hit the sweet spot. I did test the gas line and it hold pressure to the keg, I pressurized e gas lines without attaching the gas line to the keg and there was no leak - and no bubbles any place in the system. There weren't bubbles on the keg - just a substantial hiss that I've tracked down to the keg top.

I did check the and O rings look good (the keg I started with was pressurized when I got it so I know if holds pressure). I'd like to use Petrol-gel or equivalent to help create the seal but so far I can only get it via mail order.

Since I have a batch of IPA ready to keg, I'd like to get the Petrol-Gel sooner.

Any place in the DC metro area that sells this or an equivalent product retail?

Thanks