Here's why it's complex:
* Lower Thermostat Opens Sooner: The lower temperature means the thermostat opens earlier, allowing coolant to flow through the radiator sooner. This *should* keep the engine cooler under normal operating conditions.
* Incomplete Warm-Up: However, the engine may not reach its optimal operating temperature, which is important for:
* Catalyst Efficiency: The catalytic converter needs to reach a certain temperature to function properly. A lower operating temperature can reduce its effectiveness, leading to increased emissions.
* Oil Viscosity: The oil won't reach its ideal viscosity for lubrication, potentially leading to increased wear.
* Fuel Efficiency: The engine may not be as efficient at a lower operating temperature.
* Increased Engine Load: If the engine is working hard (towing, climbing hills, etc.), the lower thermostat might not be able to keep up, and the engine could overheat. The coolant might not have enough time to cool down before returning to the engine.
In short: While a 160°F thermostat *might* seem like it would keep the engine cooler, it's more likely to cause problems with incomplete warm-up and potentially lead to overheating under load. It's not recommended. Using a thermostat of the factory-specified temperature range is the safest and most efficient option. If your S-10 is overheating, investigate the cooling system for other problems (radiator, water pump, fan, coolant level, etc.) before changing the thermostat to a lower temperature.
