I am suppose to change my prius's engine oil @ 5000 miles, but I didn't because i travel a lot anyway, i brought the car to the toyota dealer two weeks ago, and it was pretty close to 7000 miles (first oil change), by not changing the oil, you can hurt the car right??
Not to worry. Though some of us like to do the first oil change before 5000 miles many people have had their oil analyzed at 5k and even 10k with very very little evidence of breakdown of the oil. Some of us are even planning to or are already stretching changes to every 10k miles. Remember that the ICE on the Prius only runs about 1/2 the time of a conventional ICE so, theoretically, should be able to go twice as many miles b/w oil changes.
