I have recently purchased my first TDI and noticed that pretty much the same day that the oil is changed it turns jet black. The mechanic said all diesels do this. From reading the other posts here, it looks like it is because of the EGR. Either way, it is contamination. I remember in the 70s and 80s, aftermarket companies used to sell an adapter that fit on the engine in place of the filter with ports for hoses to a block that held two fine filters to better purify the oil. Has anyone heard of this for the TDIs?