2002 Toyota Pickup oil consumption

I have driven this vehicle daily for 1-1/2 years. Twenty mile highway trip to town, average speed of 65 mph, drive 20 to 50 miles in city traffic and return home on the highway. The vehicle preforms well and oil consumption is minimal. A recent trip passing thru west Texas allowed speeds up to 85 mph, then climbing up into mountains. Both directions on this trip the vehicle used a quart of oil every 300 miles. Back to normal conditions the engine does not use oil. What's my problem.