Preventing cold weather issues with diesel fuel. Before diesel fuel enters an engine, it passes through a filter to strain out impurities. This filter is an incredibly important part of your equipment, but it's also a prime target for cold weather to wreak havoc. This is because there's a naturally occurring substance in #2 diesel fuel called paraffin wax. Under normal conditions, this wax remains in liquid form, so it's harmless to your equipment. The problem occurs when cold temp...