My first diesel and I’ve loved it. HOWEVER. It’s a 2016 6.7 88,868 miles on it. Check engine light came on for engine temp not up. Stopped by dealer and I have oil in the coolant overflow. They say they have to flush the system and put in new stat. However, WHERE did the oil come from?? $1600 just for the flush out. Really? 100,000 drive trane warranty I thought. Hopefully the extended warranty covers it, but I have to wait 4 days for someone to come see for themselves. Anyone else had issues with this being covered?