</font><font color="blue" class="small">( You can run a new engine 25,000 miles on the best non synthetic oil and do a fresh oil change. Then pour in a can of engine flush at operating temp. and it'll turn that brand new oil black in 10 minutes from build up that's in there from running just motor oil. I've seen this many times. It's always the same. "Well I thought my engine was clean". /forums/images/graemlins/grin.gif)</font>
I challange you to get 25,000 miles in several engines without changing conventional motor oil. Two engines come to mind; a Cadillac Catera or any Chrylser 2.7 liter engine. You will never make it to 25,000 miles without changing your conventional motor oil. One, you will void your warranty (if you have one) and two, you will fill your engine with sludge long before 25,000 miles and it will self destruct due to lack of lubrication.
Do a search on Google on these engines, you'll find plenty of people upset because they are sludged up and blown. There is no single oil brand that sludges more than any other that I've found. However, I'm yet to see one of these people complaining about their sludged and blown 2.7 liter who took care and changed their oil (no matter the brand) on a 3 month or 3000 mile basis.