Water Temperature

[blue135]

I have a 2008 135i convertible i acquired Aug 1 that i enjoy very much. Just returned from a 2000 mi round trip jaunt with 95% on the interstates. Because I like the steering wheel low, I cannot see the tops of the gauges so I run a ScanGauge II.

Now, my question: Half a dozen times during the trip, the water temperature would drop to 193 deg, then over the next two minutes run back up to 207 to 209 where it stayed most of the time. Any ideas why the sudden drop?

Other parameters:
- Water Pump has not been replaced to my knowledge
- 50,000 mi on car
- Dinan Stage 3 Software (with Dinan intercooler and oil cooler)
- Speeds were running in the 2850-3000 RPM range in 6th (man trans)
- Ambient temperatures 75-95 deg.
- Oil temps stayed in the 235-240 range according to dash gauge
- No other performance changes noticed when this would happen

Otherwise car performed great. A little turbo lag, but when spooled up, it would go. And at speed in WV mountains, rear was more twitchy than i would have expected.

Thanks for your thoughts.