My oil tank is outside. I'm not sure if it is leaking or if it's moisture. My question is, is there something I can brush on to stop any if any leaks?
Thank you

Wipe it down with paper towels and some paint thinner. Lay clean towels under the tank to see what drips, if water just ignore it, if oil you have troubles. Leaking fittings can be replaces but if the tank itself leaks it mighjt need replacement. Goop makes a plumbing sealer but you'd need to get the area pretty darn clean and dry to get anything to adhere.

Problem with old oil tanks, water and moisture get in and settle to the bottom eventually causing decay and leaks. It could be water leaking now but when that's gone the oil will come. If the tank leaks have it replaced, if the fittings leak they also should be replaced but you may have to empty the tank first depending on where the leak is. You can check for water in your tank with a dip stick and some water finder paste on the end of the stick. (paste changes color when it comes into contact with water