I always go 3,000 miles between oil changes and have done very well. When I bought my 4Runner in March of 2001 I took it on a 4 week trip in June and since it was going over 5,000 miles I decided to change to Mobil One. I was quite impressed with Mobil One at the end of the trip. Neverless I went back to Castrol GTX and went 3,000 miles and the oil looked darker and to me the engine did not run as smooth. So, I took a permanant step of going with Mobil One and deciced to go 5,000 miles between changes. After talking to people on the Edmunds Oil board I felt going 5,000 miles on Mobil One was still considered a bit of a fanatic, just as it is with regualr oil at 3,000 miles and I feel I would get better protection.
I have done 5,000 miles since and I now have 59,000 miles and I have been very pleased. At the end of 5,000 miles the oil has a light amber color or very light brown, also when I dump the oil, I can tell the difference between the oils as Mobil One comes out much faster and gets all over my hands before I can move them.
If you do go 5,000 miles it will be interesting to see what the difference is in the oil results. By the way, how much is it for a oil sample test?
