jhawkr

Both Ford and my dealer said to just drive it and see you @ 7500 miles. I believe they are correct. With new manufacturing techniques and tighter control of tolerances, most new cars do not need to "wear in" to run optimally.

Norm Peterson

Just driving it is one thing. WOT and high rpms is something else. No matter how good the machining is, you still have a little final micropolishing of parts to each other happening in the first few hundred or a thousand miles. This generates heat over and above what an engine that's fully run in will, and the differential expansion between parts will be greater (not a good thing).

There is some evidence that an engine that's run in hard will develop a small amount more power than it might have with a more conservative break in. But this comes at an increased risk of using oil later in the engine's life even if you're careful about warming it up first. Maybe this doesn't matter if you're planning for a rebuild before you get rid of the car, or rebuilding with the intent to blueprint for additional power and durability.

But for the average owner who'd rather not have the car 'down' for unexpected engine work, or those who might risk failing an emissions test due to oil burning (and all that extra unburned HC), running in hard is not generally advisable. Not worth the risk, particularly if the car is a "keeper".


Norm

jhawkr

We'll have to repectfully agree to disagree on that one Norm. I am a Quality Assurance Manager in a large machine shop. It the old days, tight tolerances were hard to consistantly maintain so we always aimed at the high side figuring you could always remove material but you could not put it back. Now, with much greater capability we can build to nominal and consistantly hold variation to insignificant amounts. Thus, journals and bearing surfaces have the consistant gaps and don't need to wear in. In addition, lubrication is vastly superior now with cars being shipped with thinner, better flowing synthetics that stand up to heat better as well. I think we need to change our thinking a little given all the advancements.

That said, I personally would never give a brand new car WOT. After shelling out over $35K for a new GT this year (I paid $500 for my 66 back in 1983), I don't care to break it or wreck it before the new car smell is gone!

Norm Peterson

I'm thinking less about holding to tighter tolerances than I am about getting the surface finishes between parts fully happy with each other. I imagine that this has been improved as well, but not to the point where it is of zero concern.

It probably doesn't take over a thousand miles any more (I've plucked that figure specifically from my 2010 Legacy 2.5GT literature, so it's not ancient stuff that I'm stubbornly hanging on to). But I doubt that it's any less than the 200 - 300 that it takes for differential gears to be broken in, either.


It might be worth finding out whether Ford (or any other mfr, for that matter) provides an initial oil fill using oil of slightly different formulation. I'm pretty sure that Honda and Subaru do, and what you might want to do if this is the case is to change only the filter early and top off with the appropriate grade and viscosity of "regular" oil.


Norm

siggyfreud

Many new engine build processes require very little break-in. While it's a good idea to be gentle to your new engine, the same could be said to acting the same way towards an old engine .

Varying the RPM's while driving is generally the recommendation, with those RPMS not exceeding 4000-4500 rpm (I think generally it's more of a percentage of max rpm than a set number). Driving for 250 miles with cruise control on doesn't count as breaking in an engine .

ShaneM

Yeah I took it sor tof easy the first 500 miles, lucky for me the trip to and from the dealer was 200. Anyway, I have had a numbe rof new cars over theyears, i think most modern engines dont care. I did the hybrid breakin thing. I drove it liek i stole it a few times within the first 50 miles on the car, it had 10 when I picked it up. Most of the driving was normal and the dealer suggested i not go over 4k the first 500 miles, at least not for a sustanined amount of time. Besides, it has a warranty. Hell mine was blown before it has 1500 miles on it.

robs

x2! Life is better at WOT! Break 'em in as you're gonna drive 'em! Naturally, it's YOUR money do what YOU want. If you're scared, baby it. If not, drive it like you stole it! Red line all the time!

sadface

its a reason i name my car b*tch most of my break in miles were me dumping the clutch with advan trac off I BOUGHT IT FOR A REASON.... fun

jhawkr

I don't think you can hurt your new car by taking it relatively easy the first 1K. But, the days of not driving over 60mph the 1st 500 miles is long gone. A good variety of stop & go, highway, and a little spirited throttle seems to me to be the way to "break in" a new car.

S281 E

Congrats on the new purchase.