My 2002 Chevy Trailblazer (194,000 miles, bought new) has a couple issues I need your advice on. First, it has taken to mysteriously losing oil. I can check the oil one day and it appears to be fine, check it a week later and it seems to be dry. I do my own oil changes and always replace 7 quarts. There is minor seepage from the gasket at the rear of the engine but I have never found oil on the driveway or noticed blue smoke from the exhaust. Over the last few weeks, I have had three instances of starting the vehicle and a getting a massive cloud of smoke accompanied by a rough idle, which lasted 30-60 seconds, followed by a smooth idle and no smoke. I am guessing this is a leaky gasket of some kind, but fearful it is something more serious…like time for a replacement. What do you think? should I take it to a mechanic or get my financing lined up? If the latter, what is a good similar vehicle these days? We enjoyed the size and off road capability of the trailblazer, but it seems they don’t make too many true off-road SUVs anymore. I have been seeing myself in a truck (the roomy F-150 or Ram 1500), but the wife wants something a little less ostentatious (her words, not mine). Thanks for the help, and I love your columns.
The big smokey cloud combined with high oil use points to a worn out engine. It could also could simply be a bad pcv valve.
I think it is worth having a mechanic find the problem. It will cost you a bit for diagnosis but the estimate will allow you to make an informed decision of what to do. Right now, you are in the dark.
As for “real off road suv’s” they still exist. Do you really need one, though? How much bush bangin’ or rock crawling do you actually do? That problem seems to need a marriage expert and not a car expert! 
Your valve stem seals might be shot . . . might even be time for a complete valve job
If so . . . yes, that can result in considerable engine oil consumption
I think we know where your oil is going 
Take off the airbox and look to see if the thing is full of oil. These have been known to over scavenge through the PCV vent, it has a rather large hole and no restricted orifice. That would be the first thing I would check…