Sludge 
2001 Toyota Highlander SUV V6 4WD 4dr SUV (3.0L 6cyl 4A)
Time to get rid of this thing
 I have owned my 01 Highlander for about 2 years. Overall it is an ok SUV, although my wife loves it. We bought it used with 45000 miles and it now has 113000 miles. We have had to replace the tires, brakes, and oxygen sensor ($200!). The heater broke and was stuck on hot for several months, the dealer told us it would cost about $1000 to replace the heater panel. After a long search I found where many others have had the same problem and fixed it. Turns out to be broken solder connections, I resoldered them and it now works for FREE! The rear axle is leaking fluid and was told by the dealer it was the axle seals...$350. Time to get rid of this thing!