Oster casings do get hot but the clippers are workhorses. The andis case does not get hot.. both will heat up their blades. Get a single speed as its the friction of the blades that cause the heat.. the blades rubbing together.
If you are concerned about the heat of the blade.. get more than one to switch out when one heats up.. keep the blades clean and WELL lubricated.. get a small piece of marble to set your hot blades on to cool them faster. My andis ag 2 speed hasnt given me any problems in the 2yrs I have used them professionally, nor have the old andis ag single speeds that I borrowed lol. I dont clip dirty hair and change my blade drive somewhat regularly.
The heat of the blade doesnt cause clipper burn.. unless you just place the hot blade in one spot and leave it there long enough to do so. Clipper burn is really like our razor burn. I havent clipper burned my dogs with a "hot" blade altho I wont clip faces or privates with one since that would be really uncomfortable. The only time I have clipper burned is when I use a short blade and I scrape the skin by being in a hurry.. the risk goes up when I clip dirty hair.
BTW dont use cool lube.. its like crack.. you gotta keep using it and it leaves a film that burns (and turns red) along with dirt and hair. Your blades dull faster.. I use this to clean my blades:
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This and oiling my blades means I may sharpen one or two blades.. out of ALL my blades(Im a pro groomer) every 4mons or so.. Some of my blades I havent needed to sharpen for over a year. Over 25 dogs a week, you can do the math
. Treat your stuff right and it will last you. Also buy yourself some blade drives.. they can go out pretty quick and will cause your blades to not cut as well.
Wahl Chromoado blades do seem to stay cooler but I nicked my girl with the 40 setting(I like it short) pretty good tho. If you keep it at like 10 then its a pretty nice clipper... I opted for the oster volt but havent used it on the girls just yet. Cuts great on the test pads, but dont know much it heats up yet.