We run aftermarket lower radiator hose heaters in all our rolling stock---tractors, trucks, gen sets, welders, big mowers.
There have been times when we had to start a welder in dead winter to jump-start a mower to jump-start a smaller tractor to start a bigger tractor to unstick a stuck truck. Life is interesting that-a-way.
As another poster here points out, the lower radiator hose heater heats the 'coolant' antifreeze mix which transfers heat to the engine block which also tends to radiate heat to the fuel tank and although the oil pan itself doesn't pick up much heat (I've measured oil temp during block heating) the warmer block itself promotes easier oil flow during cranking.
For one of our machines I looked up the weight of the engine block, assumed heat transfer parameters based on cast iron, guessed at some efficiencies of the block heater-to-water-to-cast iron heat transfer, guessed further at some losses due to radiation in a zero wind setting and came up with slightly more than 2-hours as a requirement to heat prior to attempting a start. This works for us for a 35-hp 3-cyl diesel Kubota. At 0-F I can turn the key, the glow plugs cycle in less time that it takes to write this, and she starts every time.
Five Star Manufacturing out of Tennessee markets the Kats line of lower radiator hose heaters. Assuming there is room to install, it's the easiest way to go. Another poster in this thread describes the install process---it's relatively simple.
Kats is the red-color "T" shape heater; avoid the silver-aluminum color baseball-shape that some parts houses have as a cross-reference because these 'balls' take up more space in the engine compartment near the radiator and have a lower wattage (heat) output.
Plug the heater into a timer plugged into a 'non-GFCI' outlet and set the timer to come on about two to three hours before you expect to start the machine.
We've formed the habit of using the block heater on tractors anytime we expect to start with temps less then 40-F. This because sometimes the machines sit a week or more in winter and the oil drains down, creating a harder start. Not so much trucks that run every day.
Yes, our Kubotas (and others) will cold-start at 0-F but it's unneccessarily painful.
Also, consider installing along with the lower radiator hose (or other) block heater an onboard battery float charger or maintainer.
We use Schumacher battery maintainers on everything year-round. If it's not running, it's plugged in. Extends battery life, makes all starts easier, and in combination with some form of block heater makes cold weather starts fast and easy.
Just picked up a couple more maintainers at Tractor Supply on sale for $18 each. Last forever, too. Have had one go bad, called Schumacher direct, they sent a replacement within days. Avoid Harbor Freight float maintainers as have had repeat failures---quit altogether or boil battery dry.
Concerning the Kats lower radiator hose heater, do NOT plug it in (as in a test) unless immersed in water. It doesn't take much to ruin the element if energized in air.
If in an open shed or outdoors and using a lower radiator or other style block heater consider tossing a tarp over the machine or at least over the front end. This will keep the wind from sucking out the heat you're trying to put into the big metal chunk of engine block. This is especially true if the radiator happens to point into the wind.
I'd be concerned about using propane through the air intake to get a start. We know Kubotas don't like ether starting fluid and the use of propane in this manner sounds too similar.
Years ago I pulled an oilpan off an old Chevy truck where a stick-on magnetic oil pan heater had been used. Found a burned ring of burnt oil inside the pan. So I quit that. Same with the dipstick heaters. I'd now be reluctant to use either on anything.
I've been places where we had to build a fire under an engine to heat the oil to get it going. And where we drained the oil overnight, heated it in the morning (ah the smell of bacon, biscuits, and hot engine oil) before pouring it back into the engine. Electric lower radiator hose heaters make life a bit much easier.
Please post back with your decisions and continuing experiences so we may all learn.
