I want to install an oil pressure gauge and voltmeter in my 1988 Volvo
240DL wagon. There are 2 blanks to the right of the cluster with 52mm holes under them (I wish every car dashboard was as well-designed for upgradability as this!). I'm probably going to go with VDO gauges from eGauges.com. The voltmeter install seems straightforward - wire into a wire that's hot when the ignition is on, wire into the lighting circuit, earth to a convenient place, done.Now, as far as the oil pressure gauge, should I get an electric or a mechanical gauge? If I use a mechanical gauge, should I use copper or plastic tubing to connect it? I've heard of oil pressure gauge lines fracturing and spraying oil all over the interior, which sounds like a pain to clean up even if it doesn't destroy the motor or burn your leg. I know that some copper alloys work harden, but nylon gets brittle when it's cold.
However, mechanical gauges are both cheaper and more accurate than the electric ones + sender, so they do have their advantages.
And let this not turn into a "with idiot lights and modern computers, why install extra gauges at all? discussion - IMHO, every car should have tach, oil (not water) temp, pressure, and volt gauges - fuel gauge is optional as long as there's a reserve light since I'm used to riding motorcycles.
Cheers, Andrew