EUBT, I really don't think there is much risk of a Toyota/Lexus block heater leaking. These things install very security and are extremely low-tech devices. I had a block heater on a Mercedes I drove from late 1979 until I bought my first LS in 1990 and never had any problems with it. I'd even plug it in when it was fairly warm (i.e. below 32° F. in my garage at home) just so I would have instant warm air from the heater during my relatively short drive to work.
After I had the block heater installed, it seemed like AC outlets were EVERYWHERE I parked -- it didn't take much searching. I plugged in my block heater in the covered parking lot at work, in parking lots of hotels near Colorado ski areas and in the middle of Kansas, in public parking lots and relative's driveways in northern Iowa, etc., etc. OK, I was stealing a little electricity but not once did anyone ever unplug my block heater -- and I carried a 100' extension cord in the trunk that I sometimes used to plug it in pretty far away from my car.
Of course, I really needed a block heater on that Diesel Mercedes -- that was sometimes the only reason it could be started after sitting all night in the winter at 9,000 ft. elevations. Toyota/Lexus V8 engines warm up pretty fast compared to a 1970's Mercedes Diesel engine.
Thanks Jim !
I also worry about slow oil circulation and wear on start up in very cold weather.
Your tip re. carrying a long extention cord in the trunk is a great one ,. I will check out your link .
Take care !