I think we all know how important it is to keep our oil cool in these bikes. A cooler was recommended by the factory, yet some of the coolers out there do little. I was never sure if I was harming my engine by running it down the highway in the desert on a very hot day (110 degrees plus!).
So, last summer I installed an oil temperature gauge. I mounted it to the left handle bar using a nice chrome bullet housing. I then purchased an aftermarket oil drain plug and drilled it out to accommodate the sending unit for the gauge. This way I didn't have to drill a hole into my engine case, and I can always removed the gauge if I no longer want it, and reinstall the stock drain plug.
When I drilled and tapped the drain plug, I made sure to recess the hole as much as possible so the sending unit wouldn't stick out too far. It still sticks out, but probably only a half inch farther than the kick stand bracket if that much. And since I don't go off-roading on my bike (at least not very often), I'm not too worried about it sticking out a little.
The problem I did encounter was that I had too many accessories on the fuse. My driving lamps, the fans for my oil cooler, and the new gauge were too much load for the circuit, so it kept blowing fuses. I finally ran an auxiliary hot from a relay with it's own fuse to handle the higher current. You may not have to take this approach, depending on where you connect the positive ignition power to your gauge.
I was very pleased to see that when riding on the hottest day of the year in Needles, CA on a 115 degree day, my oil never got hotter than 210 degrees. Heck, some car engines don't even go into closed loop until they reach 210!
