In Reply to: First oil change question... posted by scott on February 26, 2001 at 06:34:37:
It's true that the tiny bits of metal are partly the surface roughness that gets "polished" off during break-in. But there's an incredible amount of debris inside a brand new engine, and it's almost impossible to get it all out with block preparation, no matter how aggressively you go at it. I've built dozens of racing engines and have run Oberg oil filters on many so I could see what was circulating in my oil. I actually stopped using Obergs about 3 years ago because I got upset every time I opened the thing (which was after every session on the track). The screen had at least a few particles of metal, plus an occasional small glob of sealant or other junk (or, as the NASCAR commentator said a few years ago, DERBIS!). I worried a LOT about this for years, but I've never had a lubrication-related failure in about 10,000 track miles on my engines - so it's obviously not as big a problem as it looks like it ought to be. But the stuff is UGLY!
I'm pretty fanatical about my engine building. I'm a surgeon, so it's second nature for me to work in a sterile environment, and my garage comes close. I rinse the concrete floor even though it's painted. I have an exhaust fan and filters to keep dirt from blowing in while I'm working. I apply sealants with a syringe and needle, etc etc etc. I have the blocks baked out, then I clean them for hours with a high pressure hose and Simple Green. I've used Glyptal to paint the block interior. I've even smoothed the inside walls with an angle grinder. And there's ALWAYS some junk in my oil filter!
And when I check bearings, I occasionally find a tiny piece of something in one of them despite my best efforts. The soft metal of the bearing allows a particle to embed itself, and most of these pieces are smaller than the bearing metal is thick. So crank damage is averted if you use hard, high quality cranks and check bearings regularly.
Obviously, you don't have to do this on a street car - but you're flushing your engine when you change the oil, and I think you should do it early and often (like voting!) to minimize the risk.