Just to clarify what I wrote.. Not all splitter engines are created equal. I've got 15 year (ish) old snowblower that will start on the first or second pull ( it won't start at all if it gets rained on, but that's another story for another day ). That's a Tecumseh Snow king engine. I've got a newer Cub Cadet snowblower.. it'll start on the coldest day, on the first pull, but, even when still warm, it wants some choke to restart. I used to have a Honda powered one, that used the same engine as most other splitters.. It didn't care, set the choke, and one or two yanks, and you were on your way, regardless of outside temperatures.
My current splitter is a Canadian Tire 27 ton, with the "Champion" engine. It'll start in warm weather, with a few pulls.. But, when it's cold? Forget it, it's either Ether, or the hair dryer and a tarp, and then maybe some Ether. . It won't even pop by itself below 30 F . Once running, it's fine... just slowly run the ram with no load to loosen up the fluid.
Maybe the designers of the engine, in their infinite wisdom, didn't think anyone would use one in sub zero temps. It does however, give great fuel economy. The throttle has a "happy zone", where it doesn't shake like a dog crapping out a rusty razor blade, and a tank of fuel lasts for hours.
I could've gotten the same splitter with a Honda engine... for an extra $600.00. Ummm ..Uhh..no, I've got a couple of donor engines that will fit if the Champion engines dies.
But, ( IMHO), I think that manufacturers picked engines that were fuel efficient, and tuned the carb to meet emissions, and never really gave much thought to cold weather starting. Got a newer lawn mower? Notice how they run at a much, much slower R.P.M., than older models. Yup!.. That's to meet emission standards. It doesn't matter if there's not enough blade speed to properly cut the grass, or throw clippings into the bag. The old design motor, with a lowered R.P.M. speed from the governor, got them the emission rating that they needed for sale.
I know that, on my splitter, at 0 F, or 32 F, there's not a significant difference in the pull of the starter rope, compared to 80 F, but, at 0 F, it will not start, at 32 F, it probably won't start without Ether.. So, I'm gonna assume that it's not excess drag on the engine from the hydraulic oil in the pump, but rather piss poor design... Thanks to the C.A.R.B. standards stuffed down our throats.