I have a 2002 Toyota Highlander V6 4wd with 165,000 miles. And right now I am burning a lot of oil. About 1 quart per 300-500 miles (under normal use). Going on long trips burns an excessive amount of oil, I can burn through two to three quarts on a 400-600 mile road trip. I have not noticed any oil leaking out under the car.
I've replaced brakes, rotors, the muffler, flex pipe, and 2 frozen catalytic converters over the years, but I haven't had to mess with the engine much besides paying for a tune-up where all the spark plugs were replaced and a new Oxygen sensor was installed.
I'm trying to figure out if this is something I can take a crack at or if I'll have to take it to a shop.