First thing (more urgent): This car always has issues but then stops having them so I think it’s fine. Another one reared it’s head yesterday. Noticed a wet spot under my car that was large enough to make me think it wasn’t related to my car and so I thought nothing of it. Drove home today and coolant light came on, and then turned off. Checked the expansion tank, bone dry. Refilled, turned the car on, no leaks anywhere. The temp gauge sits just under top dead center when it warms up, and the heater wasn’t blowing hot. (Until this morning when it kind of did...). There was also the telltale white crust under the expansion tank cap like it was leaking from the top. My suspicion is a slowly failing thermostat, but other posts elsewhere said a failing thermostat shouldn't cause any kind of coolant loss of that level.

Second thing: When I leave the car in park, the gear warning light next to the gear indicator on the dash lights up. This happens about 10 seconds, seemingly after what I would imagine is the ECU running through different circuits in the car. If I put it in drive immediately, the car drives perfectly. I was told by a shadetree mechanic that he's seen it before, and he thinks its a vacuum leak somewhere thats causing the warning light to pop. I was told I have a bad DISA, so I've bought a replacement for that. Does a vacuum leak sound right to you?