1968 Ford Mustang — coolant slowly disappears without an obvious leak

If it were in my driveway, get a real battery/charging test on the 1968 Ford Mustang, not just resting voltage, before blaming a module. That's the branch I'd chase this week. I'd want a dollar figure or a measured spec, not 'should be fine.' I'll poke at it this weekend.

I'd want a measurement, not a hunch. Move a coil or plug on the 1968 Ford Mustang if it's cylinder-specific and see whether the code follows. You'll know quickly if you're on the wrong tree. A shop burned me once by skipping that step. Happens in gear, not in park, for what that's worth.

Ask what changed right before it started. Swap the cheap/easy piece first on the 1968 Ford Mustang and see if the fault moves. Save the big job until that test fails. This is from a 1968 Ford Mustang in Denver with 88,000 miles. If it doesn't change the out-the-door or the repair estimate, it's noise. Make the next action something you can finish this week. Trying not to diagnose from the couch.

Log the conditions before you spend. Write temp, speed, and in-gear vs coast when the 1968 Ford Mustang does it — then decide on parts. That's the branch I'd chase this week. On “coolant slowly disappears without an obvious leak,” that was the fork that mattered for me. Learned this the expensive way on a previous car. If that fails I'll eat the diagnostic fee.

Start with the test that can prove you wrong. Two 1968 Ford Mustangs can feel identical and have different causes, so measure before you copy someone else's repair. That's the branch I'd chase this week. That's the whole play. Parking it somewhere I can hear it better next time.