I made a post a long time ago I feel might be worth a repost. And yes, there is no debate. Let me dig it up:
The 5,000km oil change is an absolute myth, perpetuated by companies like Jiffy Lube. (How else are they going to make their money from you?)
Modern cars and modern oils can go much longer. Just as how car tech has improved since the 70s, so has oil technology. For example, many new cars are equipped with an oil life monitor, which recommend oil changes that are far longer than 5,000km.
It's hard to believe, but
the color of the oil has nothing to do with its remaining life and additive package.
One way to check is to do a Used Oil Analysis. (Collect some on the next drain with the free kit you can order from their website), then send it to
http://www.blackstone-labs.com.
You'll get a report like this, and you can determine the ideal oil interval for your car.
Amsoil 10W30 - 16,000km. 04 Mazdaspeed MX5, 1.8 turbo
Need more proof? Check out this guy running Amsoil 0w30 with a bypass filter and prelube pump in his S2000. 30,726 miles on the oil! That almost 50,000km!!
Things to look for when analysing the data.
-TBN # still exists.
-Oil viscosity are still within the specs as SAE has outlined.
So for oils like 5w30 or 10w30, 30 represents a range of 9.30-12.49 CsT or Centistokes.
Things to realize.
1. Oil color is NOT a good indication of Total Base Number (TBN), or oil life.
2. 5,000km oil change is unnecessary and is a waste of money and oil resources. (In MOST cases. If I drove an engine known for fuel dilution solely in the city, exclusively all short trips, say 1km each, then perhaps I would be a good candidate for 5k oil change interval) Another situation is perhaps if I drove a Mazdaspeed3, or GTI, where the engines have been know to shear the oil out of viscosity a little faster than other engines.
3. Oil change interval is heavily dependent on car and driving conditions. If you drive highway frequently you can extend your oil change intervals, because it takes roughly 15-20km for oil to reach full operating temperature. At this temp, you'll be able to burn off the fuel dilution.
Frequent short trips = shorter oil change interval.
By most standards, take an average Corolla or Civic. They can easily go 8,000km on regular conventional oil, even longer on a synthetic fluid.
Personally, I run 12,000km OCI in my RSX with a quality synthetic and sleep well at night. (Confirmed with some used oil analyses). I would have no problem extending out to 16,000km if I had to, the 4,000km is just a nice safety margin. In fact my last oil change I did had 17,000km. I drive 95% highway.