I'll share some of my thoughts and experiences on engine lubrication.
First of all when the manual says that you shoud change it after 5000 miles, that is (as mentioned above) UNDER NORMAL DRIVING CONDITIONS.
Wear comes from a couple things in an engine, particles in the oil is the big one, when the oil breaks down, and before the oil warms up.
You can change your oil every 100 miles if you want, but if you don't change the oil filter and keep the dirt and particles out, you're not getting anywhere. This makes no difference between synthetic oil or conventional oil. Dirt is dirt.
When oil breaks down and you lose your fluid film on engine parts, you have problems. I don't car what study was published some where, Sythetic oils will perform better in this category. I worked for one of the worlds largest engine manufacturer and they used sythetic and had plenty of data to show it's value in harsh operating conditions. (key word being harsh).
Most people seem to catch on to this one pretty easily. Before the oil warms up, you have little to no protection for your engine components. Once again synthetic oil is superior. If you want proof, I invite you to Northern Canada when the temperature dips below -40 degrees. Starting with conventional oil (even a lower 0W30 grade) sucks compared to a true synthetic oil.
Remember, you want to keep out dirt and particles, they do the most damage. The dirt comes from the air intake. The more air you put in the engine (IE the harder you drive) the more dirt you will have in your oil and the more frequent you should change your oil.
Hope that helps, sorry for the length.
|