What should you do or not do when driving your brand-new car?

Answer 1

To break in your new car, it is suggested to not subject the engine to constant speeds. Better piston ring seating will be achieved by varying the speed and avoiding hard and sudden accelerations at least during the first 500 miles. Gradual accelerations with some decelerations are the most beneficial for ring seating.

I would suggest going to the extra expense and effort to change the engine oil at 500 miles, even when the car manufacturer allows many more miles before the first oil change; most of the metallic residue produced by the initial ring and bearings break in is produced and released in the first hours of engine operation. Using an oil flush to completely remove this residue is the best practice, but avoid products intended for sludge and varnish removal, because there is no need for them at this new engine condition, and some contain extreme pressure additives that will not allow a proper break in. You can use a thinner, less viscous engine oil for several minutes of running the engine with the car stopped, and then flush it out; then, add the proper viscosity oil as specified in your owner's manual.

After this first oil change and flush, for the next one, go by your manual recommendations or slightly sooner if you wish to keep your car for a long time and in top condition. Recycle your used motor oil properly. Synthetic oils can be used AFTER proper ring seating, but there is little economic benefit in using them unless your car has a Turbocharged, Supercharged, or High Performance engine. (In dusty locations, it is better to change the oil more frequently than to use a premium synthetic that will be contaminated in the long intervals between changes.)

Some cars need no break-in period at all, and some do. Your owners manual will list the break-in specs. However, if there is a break-in period, remember that piston rings don't rely on their spring tension to seal against the cylinder bores. Instead, combustion gases work their way between the rings and the piston and force the rings outward. During the first few minutes of engine operation, it's important that the throttle be opened pretty far at lower RPMs to provide this high pressure. Otherwise, the rings won't burnish the cylinder walls properly, and the engine will have high volumes of blow-by, which means excessive oil consumption and shortened engine life. If you've ever seen the car jockeys who drive new cars off the end of the production line into the storage lot or the transporter drivers zipping up and down the car-hauler ramps, you'll realize that this all-important step has been performed for you many times. If you're installing a new engine, simply give it a few seconds of wide-open throttle in a high gear. For the first thousand miles, avoid constant speeds and throttle settings. If you commute in normal stop-and-go traffic, you'll be fine. I advise against cruise-controlled sojourns across Nebraska.