Originally Posted by ImportConvert

How to properly break in a new car:

Most of the break-in you are doing is for the gears in the transmission, and rear-end as well as the wheel-bearings, clutch, and brakes.

Avoid "shocking the driveline for about 1500 miles. This means no clutch-drops or power-shifts.

Avoid taking the car above 4-5K rpm for about 500 miles.

DO travel at varying rates of speed and through all gears, applying various acceleration/decerlation loading. A perfect example is light traffic in a 50mph city-zone, using engine-braking to aid in deceleration. Or you can get on the free way and do 50-70 sprints/decels in various gears, taking care not to rev the engine to hard for the first few hundred miles. The brakes and clutch will not benefit much, though.

This will allow the brakes to seat, the rings in the engine to seat (no, they are not fully seated from the factory. My Z06 burned a bit of oil for the first couple-hundred miles, now, not a drop in over 2500). It will also lap in the gears in the transmission and differential.

The clutch will break in at different mileages depending on stop-go traffic. You make have it broken in in 25 miles if you went through Houston when they were working on 59. You make not have it broken in int 2500 miles if you do a cross-country drive on major highways leaving it in 6th the whole time.

The reason for loading the driveline in acceleration/deceleration is because this creates a vacuum in the cylinders, sucking the rings to the wall. It also makes sure both faces of the gears in the driveline are lapped in and mesh well with each other.

This is how I broke in my Z06, and it shifts smoothly, doesn't burn a drop of oil, and works great.

My mechanic broke in my mustang gt's new crate engine by letting it idle in his shop for 30 minutes and then beating the crap out of it. It burned 1qt of 15-40 oil every 800-1000 miles.