Originally Posted by Cujet
Years ago, I worked for a company that was involved in camshaft development (and a second company that tested 2 stroke marine racing engines) . They dyno stuff was on the automotive side, I assembled engines with OEM parts and the dyno team ran them through a series of tests. Mostly for emissions and of course to meet target output. My job was to assemble the engines to a specification, time the camshafts and install on the dyno. I also disassembled the engines and measured components for wear.
We took no care to break in engines. We started them up, warmed them up to 160 degrees coolant temperature and let-er-rip. Often for long periods of time at specific RPM's at full boost. The parts got hotter than they would in any normal car. So I don't believe the Porsche explanation above. The only thing that could possibly match the loading is towing a heavy load up a long hill.
Not once did I see something wrong internally. Bearings, rings, cylinders and valves always looked perfect.
It is hard to convey just how insignificant any wear was, and how brutal the dyno sessions were. All this talk about break in really leads me to believe that rings "seat" rapidly under load and then normal rates of wear occur. No other parts "break in".
It's interesting to note that aircraft piston engine break-in includes full power takeoff and climb. Monitoring temps and watching the CHT's come down after a few minutes. At which point the rings are said to be seated and break in complete.
Hard to argue with what you experienced. You saw it firsthand. I'm more of a believer in giving it a decent amount of throttle from the beginning. I think the issue can be when you run an engine at full throttle for "long" periods of time. That can create excess heat which is what some say the problem is. Hot spots can create uneven wear patterns.
I have to say from my experience, the cars that consumed oil were the ones I broke-in too gently. However, it's hard to say because they were also known to consume oil due to the low tension piston rings (Honda/Toyota).
I picked up my truck with 63 miles. Drove it home for about 30 miles varying the rpms from 3-4k, often giving it 40% throttle. I did the same up until 1,200 miles which is what Nissan suggests. I did a few WOT runs this week. So far no oil consumption. The 4.0L though isn't known to burn oil.
I think a common sense approach is best. The worst approach is to baby it. If you go hard on it, I believe letting it cool down is what you should do.