Piston Slap: Getting Your Groove On, Long Term Edition

Tim writes:

Sajeev!

I finally bit the bullet and bought it – a 2012 Focus. I need some guidance on the proper break-in methodology for my new wheels. The car is due into the dealership within the next day or two (I had to special order a ’12 hatch, SE, five-speed in Sonic Blue, and it’s been a LONG ten weeks!). My last Focus I had to unfortunately drive from MA to FL shortly after purchasing it, and I’ve often wondered if the slight peculiar shudder at idle that it always had was due to my prolonged highway driving on that trip.

Any advice so I can have a happy decade of driving with my new motor?

Sajeev Answers:

I seriously doubt your shudder was from a break-in procedure, although it’s never a good idea to maintain the same engine RPM for a long period of time during break-in. Not that you did. Oh my, I am getting ahead of myself.

Thanks to modern materials, manufacturing and assembly techniques, the notion of a proper break-in is subjective and thus hard to quantify. Tolerances in engines are tighter for this reason: we no longer use 10w30 oil like we did a coupla decades ago, and doing so can damage a motor. Even cylinder walls are honed/sleeved far better now, making variations in driving habits less worrisome during your first few miles.

Wait…that’s not really the point, nor is it a good answer. Luckily for you, I will tell you how I broke in my special order Ford Ranger XLT (it was a LONG 7 weeks!), which now has 3000-ish miles on it.

Engines, clutches (manual transmissions, not the clutch packs in a slushbox) and brakes need to be broken in. For the motor, it’s okay to drive it a little hard, but I would keep the revs down out of respect and principle alone. For my Ranger: I drove it normally, except I’d rarely rev past the torque peak (3750rpm) until I reached around 1000 miles on the odometer. I did an oil change around 2500 miles, again out of respect…and not proven fact. Smart or stupid? You decide.

Clutches: go easy on that system, let the clutch “mate” to the flywheel so they can get their groove on. No drag racing launches! Well, at least for a couple hundred miles.

Brakes: see clutches. You want the friction material to hook up with the metal spinny parts (discs or drums) in a proper fashion. In the case of the carbon spinny bits of the Corvette ZR1, there’s a specific dance routine you must follow. And for the rest of us, including my sweet little Ranger, I loosely followed the rules of brake bedding.

Send your queries to sajeev@thetruthaboutcars.com . Spare no details and ask for a speedy resolution if you’re in a hurry.