I've been debating this idea for awhile. I *think* the oil drain plug threads on the "early" Chev small blocks (before they went metric apparently) might be compatible with the Chevy coolant temperature sensors used for the coolant temp gauge, in the drivers side head. Two thread sizes, early was large, later was small, but I believe later is 3/8" NPT. I can't find anything stating what the stock oil pan threads are though. 3/8" sounds about right for mine. Two good things there...my oil pan drain plug comes off nearly parallel with the ground, so very little risk of snagging it on something, and the later coolant temp sensors had pre-attached wiring, which would be more resistant to coming off. With the oil pan being so close to the front axle on 4WD, I think there is little risk of hitting it with anything.

Thus, I think it would be possible (and relatively easy) to use a stock coolant temp sensor to monitor engine oil temps. My reasoning of course is because of how hard on oil highway mode can be.

I have the engine oil cooler setup on my K5, so I'm not that concerned with temperature, but it would be a nifty gadget, and would be interesting to see how much of a difference there is between highway and non-highway mode oil temps. Eventually I'd like to compare oil temps with and without the cooler itself (regardless of highway mode) to see how effective it is.

I wonder if there is any location within the ECM that would allow an ECM coolant sensor to be used for oil temp, essentially two temperature inputs that could be datalogged? I suppose the stock ECM coolant temp sensor could be used, but I have to assume oil temps get too high, and would cause some bad running.

If that is possible, it would then be possible and very easy to wire up a stock truck coolant temp gauge to monitor that sender, or any gauge that operates the same way.