Really just depends, Roy. Might be months when I only drive the car a couple hundred miles a month. Or, every day or two when running cross-country, or driving locally a few hundred miles a week. The answer is every few hundred miles for me, regardless whether my diesel car or diesel truck.

My 606 had a low oil indicator light, as does my 648 - so I'm covered w/o popping the hoods/bonnets. The 648 doesn't have a dipstick, so that is done in the instrument cluster check system.

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'06 E320 CDI
'17 Corvette Stingray Vert