I wanted to see if my cheap Chinese diesel heater would still be a beast after getting absolutely abused by winter. This is its third winter, and it literally sat outside for the last month getting rained on and snowed on. It was about 15 degrees here in Minnesota (Black Friday), the unit was frozen up, and the diesel in the tank was old and brown with a little dirt in it. I hooked up a 12V lithium battery, wiped off the keypad so I could see what I was doing, held the button, and let it do its glow plug cycle. Once the fan kicked on (even a little frozen), I started the clock. After the initial glow plug timer and a bit of “is it gonna start clicking?” stress, it fired and started chooching like nothing happened. Five minutes later it’s going from lukewarm to full heat, and you can hear it settle in as the indicator squares go red-red. It even blows a little smoke at first, which is basically it burning off old carbon and that crusty fuel. Takeaway: for around $100, these diesel heaters are insanely impressive, even when you treat them like garbage and leave them outside all month.