Most of these reading unless really off the mark are good for establishing a trend. That way your instrumentation does not have to be that accurately calibrated or dead accurate, just repeatable. Start when new or an engine is good shape and call your reading normal and go from there. If you're starting from scratch with a problem then you need more information than just temps and pressures. Small variations in oil temperature can't tell you much but you can read into them a lot of unnecessary responses that won't solve anything. The kind of information that would be useful is an upward or downward trend that continues over time. If you're into analysis the acceleration of the curve is what you want to watch so you can get things fixed before damage occurs.