My 85 300d would start down to 25F with these compression numbers (dry, wet) without plugging in:

#1 - 360, 420
#2 - 260, 300
#3 - 220, 220
#4 - 100, 120
#5 - 260, 320

And my car smokes pretty bad--definitely burning oil. So, I would suggest you do a compression check to see what you're looking at. But I bet you find another problem. Especially with 100k (but like bgkast said, are you sure that's 100k?). I would check timing chain stretch and try the bottle under the hood fuel tank.