+1 on a lot of oil opinions. Here's mine:
If you use dino oil, oil and filter change at 3,000 miles or 6 months. Sold a 2nd gen 4Runner using this method with 205,000 miles on it. The guy I sold it to does the same and has over 300,000 miles on it. NO engine work so far.
If you use blend, oil and filter change at 5,000-7,000 miles or 6-8 months, whichever comes first.
If you use synthetic, oil and filter change at 7,000 - 10,000 miles or 1 year, whichever comes first. For these extended changes, a good filter capable of holding the additional particulates such as Mobil1 or Amsoil's Ea are good choices. I tow with my 4Runner and use M1 at 8,000 mile changes. Sold my previous 3rd gen with 152,000 miles using the same method and it was in showroom condition.
Towing, frequent short trips, "spirited" driving also may require you to adjust your frequencies. Just don't waste your $$ by changing it too frequently. ANY good oil (dino, blend or syn) will give you great engine service providing you change it at the proper frequency for your style of driving and the type of oil.
