Their back! 400ex oil temperature dip sticks. This dipstick uses a trailtech display (not included) that will allow you to see the current temperature of the oil while you ride. $86 free shipping within the USA.

This temp sensor works with any trailtech display. I do recommend the 742-es1 as that setup will also work with my oil filter cover. You'll also want the extension which is v300-48.

This dipstick will only work with oem tanks