[Indyuke]

Depends on what you want to keep tabs on. I would say an oil pressure gauge is a must for all vehicles, because it can give a good indication of the overall health of an engine.

An oil temp gauge will tell you the "true" engine temperature, because whatever temp the oil is, that's generally what temp the engine block itself will be. The heads will be a little hotter, and some guys run CHT (cylinder head temp) gauges. Coolant temp isn't a good indication of engine temp.

I'd rather have the oil pressure gauge.