Toyota Repair: Oil Consumption..., mile oil changes, oil viscosity

Question
Slowly the oil consumption is increasing on the 1996 Toyota Rav4 with 160K mi on it. Is there a particular reason why just this year it has seemed to have increased more than in previous years (from adding one qt of oil in between 3-4,000 mile oil changes to now adding 2 qts? It's been a record breaking hot summer in Texas,do you think that could have affected oil viscosity and increased consumption? What are some things to check?

Would the installation of a thermostatic oil cooler improve the oil consumption rate?

Thank you again!
Jim Weaver

Answer
No, I don't think an oil cooler is necessary, I don't know what weight oil you are using but try using 10W-30 during the hotter months and switch to 5W-20 in the colder time of the year.By the way quart of oil consumption is considered norma. Is there ever any blue smoke after cold starts or while driving?