In the case of plastic, the "Not to be used for motor fuel" (IF present) is a liability disclaimer, as plastic is considered to be a 'static accumulator' and can over time easily obtain and store an electric charge (think, capacitance). As such, the possibility exist that a spark can occur when making contact with another item. For this reason, plastic is often prohibited in private industry. Metal, though a good conductor, will quite readily dissipate any static charge, thus is much safer for transferring motor fuel. A good practice is to set either container on the ground briefly before transferring fuel.
3 tons