I wouldn't worry about the engine at this point(high miles) if he isn't burning enough oil to cause an issue then it wont ever be an issue since its all aluminum and I don't think J series motors came with forged pistons so there isn't extra play when its cold.
he doesnt mention how many miles are on it, and with the crowd around here it could be his winter only vehicle which drives 5k miles a year (which would eliminate the high milage theory). But oil consumption is not a linear function of time, and varies, now that we know hes planning to get rid of it springish of 2020 i would agree it probably wont make things much worse.
Only an issue when cold for the last 3 years. Odd the switch konks out at 40 and below. Should I stay in the garage? I don't understand cars...
temp switches go bad, all sensor drift over time and eventually they drift out of range, it sounds to me like yours reads colder than it should be and is causing the computer to lock you into lower gear to help warm up the fluid. I bet the upshifts are occuring later when its cold as well as not shifting into Drive (im assuming its a 5 speed which would typically make 4th gear drive, or 1:1)
Parking in the garage will help bc the car will be warmer and hence the fluid will be warmer in the morning when you start it up, so it will go into drive sooner. i dont have any issue with any of my slushbox vehicles, but my challenger when i daily drove it always had a stiff second gear in the cold until the trans warmed up some . . . (non issue anymore)