I have a leak from the red supply fitting on the bottom side of my oil tank. What is the fix for this? Replace the sealing washer or can this be tightened up in any way? Thanks for your help.
Up to you. The factory rubber will last 10~15 years. The brass could react with the oil, and start to corrode. Our API-TC oil has Sulfur compounds in it, and they are known to react with "Yellow" metals. (brass, copper, gold, etc.)
If you are going to get some thread in fittings... use plastic, and make sure the O-rings/seals are oil/Chemical safe.