If you talk to lubrication engineers, they'll tell you to change out the oil from a new car as soon as you get it into your driveway. As-built, the engines have a lot of measurable debris from the factory, regardless of how clean the manufacturer tries to build the engine.
I'm not sure, but I believe the initial oil fill has a slightly higher concentration of antiscuffing agents, which is good for breaking in an engine. The antiscuffing agents help "heal over" the areas where you get metal-to-metal contact.
I'm not sure how to handle this debate. Should you dump the initial oil charge to remove a lot of contaminants?... or should you leave the initial oil charge in the engine, let the antiscuffing agents do the work and hope the oil filter removes most of the contaminants (at least the larger particles)? I'm still open on this.
Glenmore, when they talk about varying engine speeds, the key points are the cylinder walls and rings. Varying your speed diffuses the ridge that develops at the top of the bore. Different rpm's and load conditions stretch the piston/conn rod assembly to different lengths within the bore. If you don't vary your speed, you develop a sharp ridge which can damage the rings when you finally do decide to step on the gas.
In layman's terms, some say to break in the car the way you plan to drive it. If you plan to do spirited driving with the car, then sport around during break-in.
It is also recommended to use brief full-throttle acceleration from time to time. This helps seat the rings. The rings are purposely designed to channel the cumbustion pressure behind the top ring, forcing it outward against the bore wall. The crosshatching on the bore wall acts somewhat as a file to burnish the ring, compensating for circular imperfections, eventually forming a tight 360° seal in each bore. This'll give maximum engine efficiency and least oil consumption past the rings for the life of the engine. I would recommend doing this in any gear but first. Use brief (~3-5 sec) open throttle at low rpm, not redline at high rpm!
Heck, when you think about it, sporting around should be recommended for any car's break-in regimen.
95 E320 Cabriolet, 131K
Last edited by Kestas; 12-01-2003 at 02:07 PM.