Magnetic block heaters

[dmention7]

Does anyone here have any first-hand knowledge of the block heaters that attach magnetically to the engine block/oil pan?

Obviously, they aren't going to be as effective as the immersion type heaters, but I'm talking about for cars that are garaged anyways, and just for helping to reduce cold-start wear and tear, and shorten the time until the heater blows hot air. From what I've seen, they're roughly the same price as the immersion style and the PITA-factor of the install is something I take into consideration....

 

[niterydr]

We had one for the shop truck that was pretty much a magnetic heater that you just slung under the truck and slapped it on the oil pan. Worked good in making sure that diesel could start up (plus of course keeping it plugged in).