I am seriously thinking about treating myself to a Kosco Tacho with temp gauge. The temp gauge can be plumbed in as either a water or oil temp. Water is straight forward with an adapter that is let into any of the water pipes. Oil is via a blanking plug that fits into the oil filler on the engine case. I have no issues with using as a water temp but my question is if using as an oil temp you would in effect be measuring case air temp with some oil spashes. What is the opinion of all the vastly knowledgeable bods on here? Go with water or oil?