Not staying right on top of the oil changes on modern diesels. Or unsure of what was actually put in on paid for oil changes is a reality. For example they do not even sell the right oil for the wives car in our town.


Plus expensive problems will emerge on my own even older diesel. If the right oil is not used and it is changed out more often than manufactures recommendations.


There may be a problem with some aftermarket oil filters as well. The factory oil filters are reinforced substantially. In comparison to the aftermarket one for even my older jetta oil filter. If sludging is a problem using synthetic oils there must be some form of design issue.