I have the SW gauges in my ERA and the
oil temperature gauge is mechanical. But my ERA is 10 years newer than yours. What do you mean when you say your readings are pessimistic? If you're running an
oil cooler, it's quite likely that your gauge rarely budges off the coldest reading. Mine only bumps up a bit during long road trips on relatively warm days. For that reason, I plan on swapping out my
oil cooler pancake adapter to a thermostatically regulated one during the next oil change.