DrT,

If you have not changed the timing chain in your SDL, I would highly recommend that you, at the very minimum, check it for stretch. Extended oil change intervals leave microscopic particulate in the oil which will cause premature timing chain wear. The consequences of a failed timing chain are, of course, catastrophic.

The rest of the engine may be reasonably well served by your oil change frequency.

Longston,

Fabulous reply!

Have a great day,