My 2001 V6 AWD Highlander has 138,000 miles on it. It has run nearly perfectly for eight years. I am wondering what experience others are having regarding maintenance issues as their vehicles are getting older. Basically, what issues are people running into as their mileage gets over 140,000 miles? I have read about transmission problems and oil sludge issues. Does anyone have 200,000 miles on a Highlander yet? What have they had to replace?