Changing Oil
 

just noticed the oil in our Mondeo TD is filthy, only half way between services intervals
I'll change it anyway, but just wondering, would dirty oil affect the efficiency of an engine, or just add to wear?

It will certainly cause extra wear, even with what gets past the oil filter. It will have lost some of it quality too. They always used to say that oil is cheaper than engines.

It has been known for oil not to be changed during a garage servicing too!

Les :)

Colour is abit ambiguous when checking oil condition: OIl can be as black as guinness and still lubritcate ok.

On some engines (Especially diesels), you can change the oil, and it'll go black within few months of running. Sometimes even straight after you start it up.


Thinking about it, the only diesel engine I ever worked on that always had spotless oil was our old AWD/Beford TL tipper (Perkins); But that had 3month oil changes, and only did about 10,000 kms a year. There was no real reason why it was changed, just for sakes of ease. As being a site vehicle, it had to have 3month safety checks, so it was logical to have basic servicing done at the same time (the cost of oil wasn't that much as it just used mineral multi-grade).

I have to admit that I missed the fact it is a diesel. As Shark Man says, the oil does go black quickly due to very fine particles of carbon fron the combustion process.

I used to hate working on diesels because they were so mucky in that respect.

Les :)