[Bob Lincoln]

Correct. Lockup requires coolant temp above 140F.

I recommend a Super Stat thermostat from Stant. A little more expensive, but much better performing. Your car will take a 195F thermostat.

 

[Bob Lincoln]

It will unlock if temperature is too low, and also if too high (overheating).

Running cool will kill gas mileage, promote carbon formation, which leads to pinging; also, oil will wear out and be contaminated faster.

 

[Bob Lincoln]

Might want to replace the temperature gauge "switch" - at least that's how NAPA had it listed when I thought I needed to replace it. Don't confuse this with the CTS (coolant temperature sensor). The CTS is in the thermostat housing in the 2.5 engine. The "switch" is in the head closer to the passenger side. The switch is a single wire vs the CTS two wire.

The 1-wire gauge sensor is only used for the gauge. It is not used by the computer for any decisions, only the 2-wire CTS is used by the computer. So replacing either won't help.

 

[Bob Lincoln]

Right, but that in turn won't lead to the torque converter unlocking.

 

[Bob Lincoln]

The standard one isn't. But the Super Stat is superior, doesn't float back and forth as much when it opens, and keeps the engine temperature closer to the normal range.