Almost everyone agrees that conventional oil is better for engine break-in, and that synthetic oil is better after that. when break-in is over and your engine's "normal life" begins is the source of a lot of debate. Some say 500 miles, some say 12,000. The best answer is somewhere in between most likely. Most people will say a given mileage based on when they think break-in is truly over. However, since you aren't hurting your engine in any way by using standard oil, just switch whenever you feel comfortable.

 

Engine internals need some friction to break in. Synth oil is too slippery.

 

That pretty much sums up the theory. The rings on your cylinder's "mate" with the cylinder walls during break in and the though is that this mating doesn't happen quickly enough (or at all) when you use synthetic oil. Again, the length of time that this happens is a matter of debate. I read a web page written by a motorcycle mechanic that claimed the most important break-in miles on a motorcycle engine are the first 25. I've also read on other web sites that the wearing in of some engines takes 20,000 or more miles. I chose to use dino oil until ~10K miles before I switched to synthetic. I was also more diligent about letting the turbo "cool down" during those first 10K miles.

Someone may point out that BMW's, Porsches and Corvette's come from the factory with Mobil 1 fully synthetic oil. From my understanding, the engines used in these cars are worn in at the factory, before the original owner evers runs the car.

You have a very low mileage car!

 

Dang he doesn't drive that car at all, july 02 34,000 miles

 

I think BAN SUVS would differ in opinion... either that or Mitsubishi doesn't break in EVO 4g63s at the factory.

 

No he's right. Evos are not broken in from the factory, and those which have had standard oil added immediately after purchase instead of breaking in on the Mobil 1 have typically made more horsepower.

 

 

Yes. Reduced engine wear, increased fuel economy, increased power.

 

i went to synth after 10K miles

 

Well I put in mobil 1 at the first 2k. Now it seems I burn oil I was down about 1 1/2 qt. once after like 2500 miles from the oil change.
What should I do my 03 has 13k miles now any advise should I run conv. oil or just leave it advise please

 

I used castrol regular oil until I git the 9k mile mark. Then I switched to Mobil 1 synthetic. I am changing my oil tomorrow at 12k miles and using mobil 1 synthetic as well. So far no problems I guess...

-Nigel