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.