Hummer H2 2005 - Thermostat Change - It Could Improve MPG Dramatically !

The Hummer in this video was underheating by 5%, six months after changing the thermostat and monitoring the mileage, the results were startling, a massive 20% improvment in MPG !
Who would have thought that such a low-cost part would have had such a dramatic impact, so get your H2 temperature checked with a Diagnostic Tool, with the cost of fuel today it's worth it !
Here's a run through the steps required to change a thermostat.
00:00 - Thermostat Replacement
00:10 - Technical Data
00:36 - Thermostat Location
00:48 - Disconnecting MAF Sensor
01:12 - Engine Cover Removal
01:23 - Air Intake Removal
01:43 - Radiator Hose Access
02:04 - Skid Guard Removal
02:14 - Draining Bucket
02:50 - Coolant Draining
03:02 - Thermostat Removal
03:40 - Old Thermostat
04:23 - Thermostat Housing Inspection
04:47 - Water Pump Condition
05:14 - Water Pump Housing Cleaning
06:10 - Thermostat Housing Clean
06:15 - Housing Bolt Cleanup
06:42 - Bolts Cleaned
07:11 - New Thermostat Fit
07:46 - Thermostat Housing Re-fit
08:45 - Air Intake Re-fit
09:49 - Drained Coolant Measurement
10:53 - Coolant Top-up
11:35 - Engine Run Coolant Level Check
12:21 - Check for leaks
12:42 - Final Temperature Check
12:58 - Old Thermostat Analysis

[@normt430]

Does the old coolant eat at the rubber thermostat gasket?

[@hummerfixes]

Actually have the old gasket here in front of me, it's coated with "crystalized" coolant and aluminum corrosion. The rubber has that "perished" look, perhaps due to heat and age (15 years worth) but otherwise intact. It's possible it lost some of it's sealing quality and allowed coolant to flow around it. There's always been some of slight coolant loss in the past, tightening clips and hoses helped, but I never managed to stop it completely, this is probably the reason why..