i can't answer for Rookie however you'll get as many different temp readings as there are locations for senders. I completely understand the before and after switchable set up. I've mounted in pan just cause it seems to be the hottest readings I've gotten over the years auto/marine. The oil pump is pumping a matter of inches from the sender. I think as long as your using good sender and gauge and paying attention is key. Seems like full force was going to to a switchable set up with one before cooler and one in pan if I remember corrrectly. Oil stats are key also.

I don’t have much personal experience on the matter, but I have seen countless threads argue it both ways with no definite conclusion. I think Teague runs his temp sender in the pans? I myself oversized the oil cooling system and when I got milky oil on the valve cover I put a thermostat on it and it cleared right up.

Going more of the redneck way, if you have good hot oil pressure and it doesn’t smell burnt then you’re good there. If you’re getting moisture in the valve covers then you need to adjust something. But I feel the most important duty of the gauge is tell you if something changes. If the oil is always at X temp and suddenly changes that’s the important data point more so than the actual number.

Thanks guys. Trouble shot it today using hot cooking oil heated up to 200. Got nothing on the gauge. Grounded out the sensor wire and it went full hot. That told me it was the sensor. Picked up a new one and all is good now. Temp is still only about 190 but it’s cold water the boat normally does not see.

Got a pic of the part number Incase anyone needs it from advanced auto.

Glad you figured things out Gunradd. Sorry I hijacked your thread with my question. Thanks to all that answered. Gunradd, I have Hardin Marine’s thermostatic block adapter, and it works great for getting the oil up to temp if you need to bring yours up. I am getting to 240* on a long hard run so a cooler upgrade is in my future.