I own a 2000 Tundra,V8,4WD with extended cab, originally purchased Oct. 1999. Now, with 135,000 miles. Oil, gas, and, yes, the occasional 02 sensor, together with the timing belt change at 90k, just about sums up the maintenance requirements.
When my teenage daughter started driving it to school, at about 100K miles, I had it thoroughly checked out by a local non-dealership mechanic. I was told "there's nothing wrong with that truck."
BUT, I did stumble across a recall for, IIRC, 2002-2006 Tundras, specifically for lower ball joint failures. Earlier models weren't included.
