I know a cheapcake who doesn't like changing oil because he thinks it is expensive. He use Walmart SuperTech oil, which cost about 50 cent a quart on a good day. Any way, he actually sent in oil sample to get it tested because he wanted to know how long he can go with this oil. The test cost him 40 bucks and it came back bad because he used the oil for 5k so the oil was beyond useable for anyone who care about their car even just a little bit. He still use it and change it every 4K.

His car is a nice 2003 Civic. I like the new added power it has and the 4-door model is nice looking. Anyway, he has about 20k miles on it due to heavy communiting and the car doesn't really sound good while idle. I still run very good because it is a Honda, but it have been passenger of 1998 Civic and hear less engine noise during high acceleration and stop&go traffic.