I have nver seen a SBC with a oil temperature gauge in a car from factory, that is the location for the oil pressure switch/sender. I would put the oil temperature sensor in the pan
Hmm, but that's the spot where everybody told me to install the sender, even some of the literature.
BUT!
I checked the gauges and its sender again. here's what I found: when there is no contact, two identical gauges (engine oil temp and transmission temp) have their needles a bit below 100, as shown on the picture below.
Once I give contact, the transmission temp gauge stays under 100, while the engine temp gauge shoots a little over 100, as shown below:
Interestingly, the engine is just as cold as the transmission and I didn't find any issues on the cables. both gauges share the same (+) and (-). Only the sender-cables differ, so I switched them and I get almost the same result.
The sender-cables look intact to me, so the big question is: what the fluff is going on?