I have a 1991 Z28 convertible and the gauge cluster has several empty dummy light along the top but one I was wondering about. On the Right in socket 'B' my manual marks it as not used but I can see that it has a cut out and it says 'Oil Temp'. It is located next to the Infl Res light. This one differs in that the others marked not used have no cut outs for the light to shine through so I can honestly see they are not used. Did 1990 or 1992 cars use the Oil Temp light??

 

Not to the best of my knowledge, unless the cars that had an oil cooler did. My car has that same light, but it says Oil Level. A friend of mine gave me an idea but I don't know if I'm going to do it yet. Basically, get an oilpan from an early-90's caprice, which had a low-oil light that worked. Put that oil pan and the switch on my car and run a simple wiring harness so that when the oil gets low, the switch is tripped, closing the circuit and turning on the light. Would be pretty neat, but I dunno if it would actually work or not.