My F-350 7.3 has 325k miles. If the engine sets/gets cold its really hard to start, even if it 70-80 degrees outside....if you do get it to start, it blow some white smoke.Oil pressure comes up on gauge whithin 2-3 second after you start it. Dont think its the high pressure oil pump... If you keep it the block heater plugged in it starts and runs like a champ...Glow plugs? Help, Mike

 

It sure looks like you need GLOW PLUGS

 

These guys were the cheapest for the zd11's when I needed them. Don't use anything but the motorcrafts.

Motorcraft Glow Plug ZD11

For the glow plug relay

Motorcraft Control Unit DY861

 

Yep start with testing the plugs and I would get the stancor relay it holds better than the stock one stancor number 586-902

 

Could also be getting a little warn on the injectors and injector O rings... But check out the glow plug system first. Then check your duty cycle on the HPO system.