Review on ACDelco 131 73 Professional Coolant Thermostat by Junee Mauck

With aftermarket stats, a person can choose a stat of $5, $9, $15, $20, or $30. Creepy! Whenever I can I try to use the OEM stats, ESPECIALLY if they have a rubber grommet right around the stats. It doesn't have a small check valve for venting. This feature is good, but I suggest drilling a hole in the flat "slice" area of the feature (obviously NOT in the center where the important elements are). The smallest drill you have! It really makes your cooling system easier when topping up coolant. The air is blown out of the block MUCH better. Without them, my '87 Astro would have had to "burp" a few times, and the temp gauge could get very high. With an air outlet, this is almost no problem. Just a suggestion and what I do.