Burning/Losing Oil - no blue smoke

I add 2 quarts of oil every 1000 miles. The compression test was ok. The intake manifold gasket was changed. There is nothing on the ground and no blue smoke. Recently I noticed black oily, soot on my leg when I stood behind the exhaust pipe. It’s a 2002 Pathfinder with manual transmission. I bought the car used with 75,000 miles. It now has 124,000. What would make it burn that much oil? Is it worth fixing or just keep adding?

You might not see smoke because the catalytic converter will catch oil smoke, for a while anyway.

A quart every 500 miles is a lot of oil to be using. Even though the compression check was ok, the oil control rings might still be allowing oil into the combustion chambers. I’d pull the spark plugs and see what they look like; if one or more of them is coated with heavy deposits, or slick with oil, that’ll give a clue as to the problem.

Thank you. I’ll have them take a look when I being it in this week for an oil change.

An engine which burns oil will kill its catalytic converter and oxygen sensors. Besides the piston rings, the valves seals can allow oil into the combustion chambers to be burned.
A cylinder leakdown test will reveal if the piston rings and/or valves seals are allowing oil into the combustion chambers. You may find a mechanic/shop who can/will perform the test. Valve seals CAN be replaced without removing the cylinder head.

What would make it burn that much oil?

The previous owner probably NEVER or very rarely changed the oil. The Pathfinder engines are one of the BEST and most durable engines on the road today.

Is it ok for the engine if I keep checking and adding the oil, when necessary? I anticipate the repairs to be quite exprensive. I change the oil every 3 - 4K. Thanks for your advice.