How Much Debris Is Normal After Break-In?

How to break-in a new engine is a pretty controversial topic. Some folks say to ride it like you stole it, citing the need to aggressively seat the piston rings. Other folks (likely the majority) prefer to abide by the manufacturer’s recommendation for a gentle break-in over the course of 600 or 1,000 miles.

Pablo Ortiz of Los Angeles babied his new BMW S1000RR as recommended by its German makers, but after giving his bike its second-ever oil change at 3,680 miles (the dealer performed the original 600-mile service), he noticed quite a bit of debris on the bike's magnetic drain plug.

"The only time I've seen this much debris or metal shavings this large was in the break-in oil on my 1978 Harley Davidson Sportster," says Ortiz. "I would hate to think that something is failing on my new S1000RR. Do you have any thoughts on this?"

While we certainly ride a lot of new bikes here at Motorcyclist , we're typically not the ones doing the break-in or the first service. So we posed Pablo's question to a few folks that are intimately familiar with the inner workings of engines.

John Ethell, former factory Honda mechanic and owner of JETT Tuning in Camarillo, CA, doesn't like the look of the drain plug, but he's also not surprised. "While you may not want to see this, I have seen this on quite a few BMW's. At least the magnet is doing its job," says Ethell. "This is primary gear shedding/transmission-dog shedding. Nothing to fear I believe."

Ron Wright, a service-manual writer at Haynes, has seen the inside of plenty of motors. He's a little more concerned than Ethell. "The amount of debris doesn't look normal, especially on the second oil change," says Ron. "However, when I researched these models, other S1000RR owners have posted pictures of drain plugs with similar amounts of debris. I've opened up a number of new engines and usually find aluminum slivers, which is basically swarf from the machining process. However, the slivers on the magnet in these pictures are (ferrous) metal, which is something I don't run across."

“Pablo should speak to a mechanic who services these models,” says Wright. “If Pablo's dealership says this is normal, he should collect an oil sample at the next oil change and have it analyzed, just to be sure. The next oil change will answer a lot of questions."

As Wright points out, not all the debris we see come out of a fresh engine is due to parts bedding in, but rather material that's left behind from the manufacturing process. Tim Welch, the current sales manager at Yoshimura R&D and former head of the company's vast research and development department, offers more insight into where the debris comes from and why it lingers for so long.

"With all the machining that happens when building a motor there is a ton of debris,” says Welch. “Some of it is big, some small, some microscopic. We try to wash all the debris out but with all the nooks and crannies it's tough. Magnetism compounds that. There are some machines that use an electromagnet to hold the part to its worktable while it grinds a new surface. Dull tooling requires more pressure to cut, which can result in magnetism as well. These processes can leave the part slightly magnetized attracting and holding bits of debris making it nearly impossible to get everything out.”

Indeed, it’s not uncommon to continue finding debris on the magnet and in the oil filter for thousands of miles. “It’s possible this material may be due to machining or assembly debris left in the engine that wasn’t knocked loose or picked up initially by the magnet,” says Wright. “He will probably see more (debris on the magnet) in the next two oil changes,” adds Ethell.

So the consensus is that it’s not uncommon for an engine to keep spitting out swarf and break-in debris long after its initial service. It’s easy to get riled up and worry that something is wrong, but the best course of action is to keep changing the oil and filter on schedule and to keep tabs on the crud your drain-plug magnet collects. If you start seeing more debris instead of less, then it’s time to worry!