Which V-6 do you have? Is it the car engine (the semi-infamous 1MZ-FE) or is it the 3.4 truck engine? If you have the 1MZ, particularly from 2001, then you need to watch the thing. No cause for panic, just vigilance. Recent 1MZs have been updated, mooting the sludge issue, but '01s predate the fix. Not every 1MZ will have the problem, and typically, it seems to happen with marginally maintained vehicles, although sometimes apparently, it just happens to the best of them. I had an '01 Highlander (a Camry derivative, not really a truck) with the 1MZ and never had a problem.
I've studies the 1MZ sludge issue, being personally interested (I presently own another 1MZ car, though it's got the post-fix engine). Although there are no scientific conclusions I can offer, my take-away this: use slightly over-aggressive maintenance, particularly OCI, and use true synthetic oil. The reason for the OCI is obvious. As to the syn, I'd recommend it for its greater ability to withstand a thermal challenge. Lots of members here have had great results with dino oil, but in an engine that has a proven ability to fry its oil, at least in some circumstances, I choose to stay with the most "fryproof" oils, the syns. I've run Mobil-1 in a variety of Toyotas, and had outstanding results.