Does a good engine oil get dirty quicker?

[daver clasper]

Hi

I have read that if engine oil is doing it's job, it will be quite dirty after say 1000 miles (my diesel vans have always been like this).

Mine in Vitesse is not too dirty after 3000 miles, when I change it.

Any thoughts please.

Cheers, Dave

[Clive]

Depends on how clean the engine is to start with. After a rebuild the engine oil should stay clean for many miles. As the crud builds up, the oil seems to get dirty quicker.

[Nick Jones]

I'd say a good engine will take longer to dirty it's oil.  Accumulated gunk of the ages deposited inside and lots of blow-by will turn oil black quickly.

Some oils, especially those formulated for diesel use, contain more detergent additives which help to keep the contaminants in suspension so they can be filtered oil. These tend to pick up any existing muck from inside quicker and as the filters don't get the very fine particles this might cause the effect you describe.

Diesels do blacken their oil faster but still very dependent on how well the engine has been looked after.  My near-300k A6 TDI, which has had very regular oil changes all it's life with decent oil is still amazingly clean inside and can still have vaguely translucent oil after 3000 miles, whereas my son's 160k Arosa SDI turns it's oil to black slime within a few hundred miles.  When we first got it the oil was like bitumen so I guess it didn't get much love.....

Nick