Need some help here on what to buy. Eastwood’s technical advice is confusing. Says 2 pints of fuel tank sealer will treat up to 20 gallons but a pint will only treat up to 5 gallons. Hirsh says their product treats 10-12 gallon tanks per pint. Appears to be the same (white) product. Need to treat two 8 gallon tanks that have been professionally “boiled out” by a radiator shop.