A few weeks ago I made an oil temp gauge using a digital meat thermometer from harbor freight. I followed this post from advrider: http://www.advrider.com/forums/showthread.php?t=589464 This gauge setup works awesome. I checked the accuracy by comparing the oil temp readings from the home made gauge with readings from an infrared thermometer. I checked temps with the infrared thermometer on the oil lines and the reservoir in the frame. Temps were the same as the home made gauge. If you decide to make this gauge and you can’t find a 20mm bolt a ¾ 10 will work just fine. The thread pitch and diameter of the bolt are almost the same as a 20mm. The original battery died pretty quickly on the thermometer. The batter was an SR44. Walmart carries a LR44 3 pack for just over $5. The LR44 is the same size and voltage as the SR44. The thermometer can be opened up using a little flat head screw driver. The only other suggestion I might make is to run the oil level above the halfway mark on the dipstick. This temperature gauge just barely makes it below the half way mark on the dip stick. Even though oil coming in from the return line probably sprays all over it, I would run my oil level close to the full mark just to be on the safe side.