Dirty derv oil?

[lisbon_road]

I know this is not completely relevant, but running cars on lpg, the oil looks clean even after (say) 8000 miles.  I change it thinking perhaps I should, not because it looks horrible.  

[shedenvy]

When I cunningly smashed the sump on the Multipla, and a replacement was tiger sealed on and new oil & filter changed, the oil stayed clean for 1000s of miles (I do 500 a week).  I think the key point is that my MAF was unplugged so no EGR flowing.  For the most part a common rail, boosted diesel is very clean - it's just EGR which makes it sooty again.

If you have a DPF fitted and no vaporiser then you have Diesel in the oil as well as soot.

[mat_the_cat]

39 minutes ago, lisbon_road said:

I know this is not completely relevant, but running cars on lpg, the oil looks clean even after (say) 8000 miles.  I change it thinking perhaps I should, not because it looks horrible.  

Agreed - it's a much cleaner burning fuel. Although you will still get the degradation of oil from the temperature cycling, shear and oxidation for example, so you are right not to leave it in there for longer.

[georgeinabz]

I’ve had a few diesels with higher mileage that have made clean oil dirty within 500 miles. Diesels quite often sound a little quieter with fresh oil - does it sound any different when running?

500 miles that’s good ,mine is coal black in 50 miles , and don’t get me started on the crap around the egr valve took days to wash off the paws


Sent from my iPad using Tapatalk

[bunglebus]

My EGR got blanked off years ago!

[Spurious]

There's also crankcase ventilation which will mix manky diesel blowby fumes in the crankcase. I've never got more than a few miles and then it's a lovely black.  Petrols stay cleaner for a lot lot longer, couple of thousand miles since I changed the oil in the Audi and it's still somewhat brown.