I have a 2008 Chevy Suburban (original owner.) I typically remember and observe how all the gauges are working properly like clockwork. Here's the rundown.

1st Coolant System Service 05/15/13 at 54,223 miles. Done by a Chevrolet Dealer. After the service the temperature gauge worked as usual. To give you an idea of how my Suburban heats up over the years... I can basically drive anywhere for 15 minutes while the outdoor temperature is 40 degrees and the gauge would just barely hit middle. Even short drives of 10 minutes going 45 mph it never would reach middle on the temperature gauge. I could only conclude the cooling system is working perfect in my opinion.

2nd Coolant System Service 02/17/23 at 76,998 miles. Again, before servicing I wasn't experiencing any cooling issues. Temperature gauge was working "as normal" in my opinion. The service was just precautionary to get the old liquid out. The service was done by a reputable mechanic who I've known for the last 7 years. In my opinion... very knowledgeable and respected. I gave him the shop supplies to use. Prestone GM Certified DexCool Antifreeze and distilled water to do the service.

After the service was complete I have driven the vehicle 3 times. What I've noticed differently... The engine heats up on cold starts much quicker than usual. The outside temperature was about 40 degrees and the normal places I've been driving too... it seems the temperature gauge reaches 12 noon about 8 minutes faster than before. Meaning the engine is getting hotter. Also, when I crank up the heat at MAX in the cabin... when I put my hand up to the front vents... the heat is amazingly HOT. I literally have to pull away my hand from the vent because it's so HOT. I don't recall my heat vents working that well in the cabin. Now, keep in mind the needle sits just left of 12 Noon. We're talking a dot or 2 dots to the left of 12 noon on the temperature gauge. It hasn't gone past 12 noon yet (towards the right.)

My question to the forum is... should I be concerned? Nervous? Was the Coolant Service done properly? The Temperature Gauge hasn't been the same since... it's just disappointing because I don't want this engine to run hotter... just because I was doing simple precautionary services.