I'm going to be picking up a new car tonight (2006 Hyundai Elantra VE 5 Door Auto) so I've been doing some reading on the best way to break it in. However, I've got a few questions regarding some of the common recommendations.
The stardard recommendation that you always read is for the first
1000km or so: don't accelerate or break hard don't let the RPMS go too high don't drive at a constant RPMMy question is regarding item 2 ... not letting the RPMS go high. I don't understand how it harmonizes with some other information that I've read on the web. This post explains it real good
The reason for this is that when the car is brand-new, the cylinder bores wear at a far more rapid rate than after the break-in period. BTW, the accelerated cylinder bore wear is the reason that you have to change the oil more frequently when it's brand new. Anyway, the bores and rings are designed to wear until there is a smooth seal between them for the best compression. At different engine speeds, there are infinitessimal differences in the total piston travel, i.e. when the engine is turning faster, the pistons move a few thousandths of an inch higher at TDC and a few thousandths lower at BDC. By running at a steady speed during the break-in period, the cylinder bores will wear disproportionately in the range covered at, say, 2500 RPM. Then, when you exceed 2500 RPM, the rings will have to travel outside of the worn-in area. I'm not sure if there's any danger of actual ring breakage, but at the least, it can't be good for the rings.
*****************So if you don't create high RPMS during the break in period wouldn't you in effect be creating the same problem as a constant RPM ... ie: the section of cylinder contacted only during high RPMS doesn't get worn in properly?
I'm might be reasoning things out wrong ... so please let me know. Item 1 (easy on the gas and brake) and item 3 (vary RPMS) makes complete sense, but I'm pretty confused on the low RPMS thing ... when I get the car should I baby it with low RPMS or will it be better off to vary the RPMS accross the whole range?
Thanks, Harry