My local dealer did the first oil change on my 6.7 at 100hrs/4251kms. I did the second oil change myself at 242hrs/11853kms. (after a 3000km trip towing my 9000lbs toyhauler trailer) Recently the overhead console read "oil change required" this happened at 324hrs/15417kms.(after mostly easy driving no towing) I did this oil change myself and reset the overhead console.

Here is my question: Did the indicator come on because the oil really was dirty or did it think it was time for its first change?

There was never any message on the overhead for either the first or second change. I still did the reset procedure after the second change even though no message was displayed.

Any thoughts?

 

Since you said you reset after the second oil change, I would say that your driving style during the last oil change interval required more active regenerations (i.e. short city type driving). More regens will cause the oil to become diluted with fuel. The change oil indicator algorithm is designed to "detect" oil dilution caused by excessive regens. Manual states to change oil when indicated or at 7500 miles which ever comes first.

If you reset properly, I'd say the oil was really "dirty" (probably fuel diluted). One indicator is the oil level creeping up the dipstick so that it is overfull. Only an oil analysis will really tell.