95 LS , 150k and no issues with vehicle, regular oil changes and services. Now starting to notice oil loss at a rate of a qt per 4-5 tanks of gas. More if running hard up hill freeway all day. No noticeable mileage change, no smoke, no leaks at all ( not one oil drop !). Vehicle runs great and occasional " check engine" light for a few seconds every 2nd week or so, mech checked it and came up throttle body malfunction, mech not worried about it. Where is my oil going?

 

Check your coolant.

 

I have experienced the same problem with my '00 Pajero. It's time to replace your PCV valve.

 

valve seal maybe?

 

That would make it smoke.

 

where i'm staying valve seal problem does not always produce smoke.
only engine oil will be reducing

 

Coolant fresh and no oil contamination, Going to try the PCV and see what happens

 

its quite normal for any engine to consume oil.
Just because you cant see it doesnt mean its not entering the combustion chamber. A quart every 4-5 tankfuls is actually acceptable on a brand new car.
And it so happens that the 3.0 liter in your montero uses a LOT of oil as the mileage accrues.

 

So you are saying that it`s acceptable to consume a oil change worth of oil for every 16 tanks of fuel?

 

Hogbygardd, I think one of the easiest ways to check if you're burning the oil is to see if there's an dark yellow-ish residue left on the right hand side your rear bumper (by the exhaust). It's easy to clean off with some Simple Green, but back when I had bad valve seals, the right side of my bumper was all coated in that stuff. Change your PCV valve and let us know what happens.