Here is something else I've been thinking about. Rod and main bearing life. 90 ctd bought new and has had a good service life for oil changes since new ~ 5-550,000 now, oil pressure remains steady to this day. I haven't found mention of it in my literature.

 

Just run it.

Or if you want to send some oil samples to Blackstone Labs they can tell you if they find a lot of bearing material [or other stuff-anti freeze. ETC] in your oil.

 

I'm inclined to just run it. Back in Oct of 89 when I was thinking about a new truck and talking to dad about it he told me it would outlast me. I was skeptical but bought it anyway.I had no experience with diesels and all my mopar knowledge was 440,426 hemi and 340s

 

If it isn't broke, don't fix it. Not unusual for a Cummins to hit half a million miles. Just keep up good maintenance practices and take care of anything that does break immediately.

 

Best $35.00 you could spend once a year to see what is going on inside. My .02