Engine Heater Worth it?

[ProjectM96]

I heard on the radio show car talk that these engine heaters, or oil pan heaters eliminate 95% of wear on the engine.

Since our Boxsters take forever to warm up the 9.2 quarts of oil, and the engine feels noticeably different when driving past 3000rpm after a cold start, I was thinking of buying one of these heaters.

However, I do not have a garage. It seems like all of these have to be plugged into an electrical cord. I cannot find one that works on a rechargable battery.

If I buy one, I would not want to leave it outside on an extension cord that anyone could use.

I heard of a few types. One is a magnet. You stick it to the oil pan so you have to get under the car to install and remove it every time.

The other is a dipstick with a heating element. But our dipsticks are very long so I doubt I would find one that fits.

Does anyone here use an engine heater or could recommend one for outdoor use?(no garage)