Replaced my Gas tank and can't seem to get the filler neck grommet seal to Seal... Do you use a certain RTV? or even use RTV.. any tips would be great.

No RTV! Will be a major failure.

Make sure its super clean and lubricate seal with silicone during assembly.

ok... any particular silicone brand?

Thanks for the help!

Vaseline works.

I agree. Use Vaseline instead of silicone. When I said silicone I meant just silicone spray lubricant. I just used silicone but Vaseline would be better..............

I use plumber's silicone grease from Ace Hardware but for some reason I can't get it to come up on their website.

Thanks for all the advise! Much Appreciated

Make sure the neck is clean and smooth. Some necks have undercoat or dirt on them and won't seal well when re-positioned.

I use a thin smear of bearing grease to let the neck slide in smoothly. You should not need a sealant. Gas eats RTV, bearing grease and just about everything over time so just enough to lubricate the slide in is all you should need.

Did you get a new seal? Does it fit the neck snugly? There was a run of bad seals a few years back IIRC.

I replaced the seal... bought on ebay it was leaking pretty bad... when I took it apart to see why, the seal shrunk and was almost egg shaped and an 1/8 of an inch shorter then the next one I just put on. I just ordered one from Detroit Muscle.. hopefully there good...

At one time I would order a new seal from mopar but for a late 80's early 90's truck. It was a little different looking but fit fine. They may be NS1 by now.

I feel confident the Detroit Muscle ones will be good.

Yes, try and get a mopar seal. Some of the aftermarket ones are junk. I`m not sure what year you are working with but 4002010 fits quite a few years and is still available.

IMO silicone is the most logical but worst thing you can use. Get that stuff on metal or paint, and it's basically there forever. Get it on your hands and touch something, same thing. DAMHIK.