I recently switched oil brands from Mobil delo 15w-40 to the Chevron Delo 15w-40. I was shocked to see that my oil consumption reduced from 1 quart of oil every 400-500 miles to 1 quart every 1000 miles. Has anyone ever seen this before?

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82 240D - 257k
84 300d - 86k

Did you mean you switched from Mobile Delvac 15W-40 to Chevron Delo 15W-40?

Delo is a superior oil. It uses a better base stock.

Yes, That is what I meant. Is that kind of oil consumption reduction common?

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82 240D - 257k
84 300d - 86k

Should not be common. Delvac is a good oil but Delo is even better, especially in low temperature performance (lower pour point and lower cold cranking viscosity).

Delo meets Mercedes-Benz oil specs of 228.1 and 228.3.

Delo uses a more pure base oil (Group II) that is called IsoSyn by Chevron and Delvac uses a mixture of Group I and II. On the Chevron site, they tell you the exact percentage of what's in the Delo in its MSDS.

My 300d had always used castrol 20-50 by the PO. I was using the same thing till I found this forum and saw the oil discussions and switched to delo 15-40. I noticed way less leaking from the places that had leaked since I got the car. Turbo drain seal, lower oil pan gasket, oil filter stand. Turbo drain seal finally went a couple of weeks ago and had to be replaced. I was adding a qt. of Castrol every 600-800 miles, with the Delo I only added every 1300-1800. Since I have replaced the turbo drain seal and the oil pan gasket I don't see any oil drips under the car. May make it oil change to oil change now.

I also noticed that I have not been leaking any oil. My leaks were not major, but they were there. Now my driveway is clean!! If anyone wants a few gallons of Mobile delvac 15w-40 I will gladly give it away!! I will stick with the Chevron.

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82 240D - 257k
84 300d - 86k