A quart per 1000 miles or more isn't high consumption.....ours is averaging around 1200 ish per qt on Mobil.....we'll see what it is on the diesel oil. So far I've driven it about 200 miles with no issue except smooooth running.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

I wouldn't think spark plug fouling would be a problem until you're burning a quart in under 1000 miles or so.

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1987 W201 190D

Diesel rated oils are one of the best oils we can use in our gas older design engines. My '90 103 (112K) has used nothing but 15W40 since new and so has my '77 230 (153K). Neither consume more than 1/2 qt. between oil changes. Also, these engines seem to consume a little oil after a change and then settle down at about the half-way mark on the dip stick. Mercedes recommended these oils for their gas engines and the oil jugs used to say "For Diesel Engines and Hard Working Gas Engines". These oils still have more anti-wear additives then most gas engine oil formulas today and seem to perform better in older engines built to different tolerances.

I like the advertising concept of the Valvoline Max Life. I've never researched it's actual properties, but they advertise it to be formulated on the high side of the rated viscosity, and to have additional seal conditioners and detergents. All these sound good fo older engines. Been using the 10-40 since it came out a few years ago.

DG