I just bought an 03 Sierra Duramax and I am new to the diesel world. This is the first diesel truck I have ever own and want to change the oil since I am not sure when it was changed last. I have own several gas car and trucks, but my friend said that changing the oil in a diesel truck is different than a gas engine. He told me that I have to put oil in the filter first before I screw it on the engine. Is this true? Is the process for changing oil on a diesel engine any different than a gas engine? Also what oil do you guys recommend? How much oil does this engine take?