It would be better if it only used a quart every 3 or 4 thousand miles, but being older and likely high mileage, a quart every 800 miles isn't all that unusual. The point where it's too much oil consumption is a bit arbitrary, but it's generally accepted that a quart every 500 miles means it's time for major engine work. This is assuming the oil is being burned. If it's leaking then leaks should be dealt with 1st (most oil leaks are not that difficult to repair).
There have been some discussions on the forum recently regarding ways to improve oil consumption issues. Here's a good thread you may wish to review:
http://www.toyotavantech.com/forum/s...s-on-87-Van-LE