Hello
I came across a 00 Excursion with 200K miles from a dedicated diesel truck owner. He had it 9 months but wants to downsize.

On start up he says it produces white smoke for a few minutes and thinks it is either a O ring on a injector, glow plug or glow plug relay. What does white smoke at start up mean? He says it will do this when it isn't plugged up on a cold day otherwise there is no smoke. Is this something to worry about?