I gave up on the Lower hose heaters on tractors and vehicles.
They always seem to fail at the worst times, or somehow work themselves into leaking, or degrading the hose.
Some folks have luck with 'em, I don't, and ya ain't gotta kick me twice.
So it's been a plain old KATS(Made in USA!!) magnetic block heater for a while now.
They run about 30 bucks at Auto zone and TSC.
Just slap 'em on the oil pan or block and plug it in.
They only get up to around 140-150 degrees so they don't scorch oil to the pan like some do, but the trade off is that they kinda suck if it's really cold and your equipment is out in the wind where the thermal mass can cool faster than the thing can heat.
I also don't use 'em unless it's below freezing, so I don't get scorching, or oil breakdown issues.
They also come in handy for other uses where a bit of heat will help, like pre-warming Hydraulic tanks, thawing out frozen door locks, warming up gelled fuel in the tank, thawing iced up fuel filters etc.. Lotsa uses.
Stay safe!
Dingeryote