[modern] Intermittent Trunk Locking

For several months I have found that my trunk does not always lock with
the remote lock/alarm (doors all lock). I have tried the turn right-turn
vertical key dance; it will lock/unlock with the remote for hours or days,
but eventually will not lock. Is this a symptom of a failing battery
(probably original - “Jaguar” label) or something worse?

I recently replaced the thermostat (with great help from the archives) and
found that the Stant 180 degreeF thermostat works fine for the '94 4.0
engine. I also replaced the tires with Michelin Pilot XGT V4s; these seem
quieter, smoother, and better-handling than the Pirelli P4000e. The “Pilot”
type is M’s model for “low-flyers” - $148 each installed. More data for the

Bruce Bordner
1994 Vanden Plas, 47K miles (7K since I bought it in 9/98 - I just can’t

You should have got the stant thermostat that is made for
the Jaguar…its a 192f one.
Running the engine cooler than its supposed to is not good at all.
Besides the fuel mileage, the volatiles wont be cooked out of the oil.
Running an engine cooler than its supposed to be is much worse
than running it a little hotter…modern oil has no problem with
heat, but cant do much about the buildup of moisture and unburnt
gas from a cool engine.

1990 XJ6