I just installed an Autometer electric oil temperature gauge in my console gauge pod and I have noticed some weird readings. I think that it may be due to the location of the sending unit, but I'm not for sure. The sending unit had 1/8" NPT threads on it so rather than remove my oil pan and weld in a bung, I just removed the drain plug, drilled the 1/8" NPT pilot drill all the way through, then tapped the head end of the drain plug for the sending unit. The drain plug was fairly thin in a few places, but not too bad.

Anyway, when I'm driving down the road at any speed, the oil temperature only reads 160 degrees. When I stop at a redlight, it shoots up to 210 fairly quickly. This is the opposite of what I expected. Could the air flowing over the sending unit affect its temperature that much? Am I missing something? Or, is this just normal?

Anybody?

air flowing over the sender shouldn't affect it.
How far does it stick thru the drain plug, is the end of the sender completely exosed in the pan?
Are all the wires tight, good connections, solid ground on the guage?

And engine is cooled by water AND oil.
There is a great proportion of heat released from the sump surface and tappet covers. Hence why sumps are husually painted black and aftermarket/z28 covers are finned.
While moving there is greater heat given off, but when idle, unlike the radiator there is no fan to keep air moving over these areas.
polished sump/tappet covers release even less heat..nice for show dont work well for street/race.
Also at idle, the sensor will not be in an area where there is a great flow across it (as there is with a water temp sensor) this would contubute to the high temp readings. While the car is moving there is more oil movement...

210 is not excessive for the oil at idle under these cirumstances

No air flowing over the sending unit plus extra heat of pavement, i think you got it right
River

All the connections are tight. The sender does not stick out of the drain plug, it is encapsulated inside it. The ID of the hole that I drilled through the drain plug is slightly bigger than the OD of the sending unit, but not by much.

I know that it isn't the best place to put the sender, but it was the easiest. I really didn't want to remove the oil pan, just to install an oil temp sender. If it was a stock oil pan, it wouldn't be too bad, but I have an aftermarket, baffled oil pan and I don't know if I could maneuver it enough to get it out with the engine in the car or not.

I just thought it was odd that I was getting higher oil temperatures while sitting still. I figured that the oil would be hotter while it was under higher pressure, and being thrashed around inside the engine at higher RPM. I guess I need to find a good curvy road or a race track to put it through its paces for a little while to see what the oil temp does.