you can make a glow plug heater by using a cheaper glow plugs and a pipe to drill glow holes.Then reduce pipe to 7/16s.But you need to run filter after it as tiny bits of carbon can mess up a IP
I use fatty wagons injector line heaters,to make sure my oil is over 180 degrees.I haven't run my emergency fuel for over a year and a half.storing it in case of war

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1999 w140, quit voting to old, and to old to fight, a god damned veteran