I have found an oil temp gauge very informative over the years. I hate not haveing one in the 300D, and will probibly install one eventually.

A thing you notice with an oil temp gauge, is that it takes a LONG time for oil to reach operating temp. You can easily look at the coolant temp gauge and say to yourself "well it's plenty warm to drive normaly" when in reality the oil temp is still quite low, something I think that's worth noteing. In addition, prolonged highway running under high boost and especialy in harsh, hot weather will often creep oil temp up a good bit and is not evidant on a coolant gauge, there have been times I've seen oil temp in excess of 250 degrees F, which is a little much for my taste. You'd never know that with just the coolant temp gauge, and it's debatable weather you'd see it with an EGT, I kind of doubt it.

It's far from necesary, but I think an oil temp gauge is definantly worth haveing, and practicaly mandatory is your consistantly driving a turbodiesel(or any turbo vehicle really) hard. Another under-valued item is a trans temp gauge, heat is a serious killer of slushboxes, and you really ought to know what there doing.

My experience..

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One more Radar Lover gone...
1982 VW Caddy diesel 406K 1.9L AAZ
1994 E320 195K