Harley makes a digital gauge that measures oil temps and also the newer ones measure the oil level too without removing the stick. There's been many of these units going belly up and the readings don't work after a period of time and they come at a healthy price.
I like the old analog units and there's a tip when using one of these units.
If you position the gauge in the filler neck (they rotate to any position on most models) so that your normal operating temps have the pointer facing straight forward, you can tell at a glance when your temps are normal without having to read the numbers and can be done on the fly without taking your eyes off the road ahead for any length of time.
Works well and have done this on many bikes.
I like the old analog units and there's a tip when using one of these units.
If you position the gauge in the filler neck (they rotate to any position on most models) so that your normal operating temps have the pointer facing straight forward, you can tell at a glance when your temps are normal without having to read the numbers and can be done on the fly without taking your eyes off the road ahead for any length of time.
Works well and have done this on many bikes.