At about 120K I started noticing smoke in the exhaust and some of the other signs of injectors needing replacement. I took a quick oil sample and sent it off for an analysis. I dropped the truck off at the dealer a couple days later and they started replacing injectors and I had them check and replace the glowplugs at the same time.

I kept pestering the company doing the analysis (I sent the sample priority mail) but they were slow in getting the sample posted to the internet and even though the turnaround on the truck was 8 days (!) the oil sample results did not get back to me for over three weeks. They didn't seem to be able to tell me over the phone, but kept assuring me it would be posted "tomorrow". The truck was still apart when they actually performed the analysis, and a quick report would have allowed the dealer to take a better look while things were apart for injectors. At that point, pulling the heads would have probably added only a couple hours of labor.

Truck got buttoned back up, runs like a dream, mpg up about 1-2 on the first tank and the analysis FINALLY gets posted and shows no fuel in oil but Potassium at 42 (previous readings were 0/3/5/2 on successive samples) with an evaluator comment to check for source of coolant leak.

While the coolant looks a bit low in the overflow tank, I have to admit that I hadn't added a drop or changed it in the four years I have had the truck and it was not something I looked at very often to begin with.

When the injectors were done, I provided the new oil and filters for the changeout. Tech added 12 quarts (I had provided 12, but told him to only add 11 on the changeout (it was in two and a half, 5-qt containers) so I drained the excess. I did notice in the drain container a few very-small (pin head size) bubbles in the oil. Today the DIC low-coolant warning came up on a start and I pulled about a 5-oz sample from the drain pan and put it in a glass jar so I could let it sit and see if there was any sign of separation in the AM.

It is not really apparent to me if I am making any oil. As I say, the truck is running great, so it is not like I suspect a cracked head or blown head gasket. I had thought I would get 1000 miles on the new injectors and send in another sample to see if it would still show a high potassium reading. Wondering now if I should even wait that long or just get it into the dealer.

Worst part is, we plan to head south for the winter in a couple weeks or so, and I am starting to wonder if I should be towing a 14K lb RV down to the DC area or delay the trip a bit while getting things fixed.

I am glad I am sampling, otherwise I probably would have not known for a long time about what may be a coolant leak.

Advice?