I grew up in the Chicago area and now live in the Twin Cities. I've got an engine block heater in a box waiting for me to install it in my '01 EX. Here's why:
- There is essentially no down side to having one. In particular, with Honda's design, i.e., it threads into the block, vs. either expansion plugs or in-line heaters, there's virtually no probablility that it'll leak, unless the heater leaks itself which is highly unlikely.
- While it may not be necessary to start the engine in "reasonable sub-zero F" (an oxymoron if I ever heard one) temperatures, it certainly can't hurt.
- Since it actually heats the coolant, not the oil, it allows the heater to produce useful heat sooner.
If you are subject to sub-zero temperatures, I strongly recommend synthetic/semi-synthetic oil. It alone allows the starter to spin the engine much better than pure dino.
My car sits outside. When I decide to connect the heater, I use a heavy duty timer set to turn on a couple of hours before I expect to leave the next morning. I may also run it for a couple of hours inbetween, although the benefits of this are certainly arguable.
You can purchase Honda's heater for about $35 over the net. Installation appears to be simple, but maybe messy. You should probably have some extra Honda coolant on hand before you start; you'll almost certainly lose some coolant in the process. The $35 seems to me to be an acceptable insurance premium to avoid just one instance of NOT being able to start the engine when you need it. The comfort of having the heater work sooner is an added bonus.