I have gone through a lot of pain dealing with leaks in either fuel and high pressure threaded fittings. This can be true of biodiesel or vegetable oil conversion systems. Vegetable oil has an amazing wicking ability and will leak out of the slightest thread flaw. This is particularly true if you use iron pipe fittings or fittings of dissimilar metals. If you are having problems with leaks in the threads subject to high pressure this is also the ideal sealant
Over a year I tried at least 20 different thread sealants with complete success. I finally decided to try epoxy as epoxy would allow me to align a fitting without having to get it super tight. I must have tried at least a dozen different types of epoxy. Some dried to fast, some where too thick and did not flow into the threads, and others plain just did not have the strength. After much trial and error I finally found the ideal epoxy. This specai grade epoxy has great flow abilities and won't set up too fast on you. Takes about a hour to get tacky and a full 4 to 6 hours to get hard This stuff has amazing griping qualities and will not break free when hit hard (like a lot of epoxies I tried).
PLEASE NOTE: If you ever decide you need to remove the fitting you will have to heat it with a propane torch to break the epoxy loose. You will NEVER get the fitting lose without burning this epoxy. That is just how tough the seal is.