[skyship007]

If you read my post again you will see I did not say richer, it just takes longer for the engine to warm up if the EGR is deleted, so the mixture stays in rich burn for longer if the EGR is not functioning.

I agree with the rest of the last post, although Carbon loading of the oil does not matter for a diesel if the oil filter is functioning and the oil is changed before it turns acidic. It does that when the total base number (A direct measure of the amount of active detergents left in the oil) is below the total acids number, which is the game over point for the detergent/dispersant additives in the oil, so any new blowby Carbon will start to form clumps that will cause long term sludge formation in the sump. Before that cross over point (If you don't know the TAN of the used oil, then it will occur when the TBN is below one third of the new oil figure, which is around 3 for most good oils, but gets serious below the 1 min figure quoted by most oil labs).

Oddly enough I've not heard of anyone deleting a petrol engine EGR before, probably because they stay clean for a very long time, whereas a diesel with bad compression or bad injection based in a city can dirty them up a lot faster.