Car Advice

How to run in a new car

When you buy a brand new car with only a handful of kilometres showing on the odometer, you have to go easy on it… Here’s how to run in a new car.

A CAR IS A COLLECTION OF VARIOUS components bolted or otherwise connected together, particularly the engine. When anything is connected to anything else there will be a tiny mismatch here and there, and this is known as a tolerance. The parts need to settle into through the tolerances into their best working positions, gently, and this is what running in is all about.

In particular, the piston rings need be bedded in to the cylinder walls. The process for running in will be described in your owner’s manual. Typically it involves driving gently for around the first 1600km without exceeding an RPM limit, but there’s a bit more to it than that. The trick with running in a new car is varied engine loads, not just racking up the kays.

Cruising on the freeway in top gear for hours on end isn’t ideal either as it doesn’t variably load the engine, so try accelerating in higher gears with more accelerator than you’d normally use, varying speed, cruising in the gear one down from the top and so on. But don’t labour the engine, which is forcing it to use far too high a gear for the conditions, for example fifth at 40km/h. And do all this only when the engine is warm, which means the temperature gauge has got to around halfway and has stabilised…

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Drive gently and vary the rpm when running in your new car

In fact, any hard or fast driving is best done with a warm engine, whether the car is run in or not. And on that subject, idling a car before driving doesn’t warm it up. All you’re doing is using fuel and increasing wear while the engine runs cold. Instead, drive the car gently – light acceleration – immediately after starting so you’re applying light load to warm the engine up, but not enough for undue wear.

If you need to exceed the RPM recommendation during the run-in period then feel free to do so, on occasion, preferably when the engine is warm. You might want to get a feel for the acceleration you just paid for and not want to wait till you’ve run it in, or you might just need the extra power in a hurry. You won’t hurt the car, but contrary to many Internet forums it’s not a good idea to race a new roadcar engine at high revs in order to break it in.

Another run-in instruction typically recommended by the manufacturers is to keep the car lightly loaded, so avoid the heavy loads and bigger trailers, at least initially. Sometimes other new components need a bed-in process too, and brakepads come to mind. Of course, it depends on the pads and the car, and the workshop may do it for you, but if you get new brakes fitted ask about the bed-in process to follow for maximum stopping power and pad life.

While modern cars are better built and more reliable than ever, there’s still the possibility of a problem. My Toyota 86 had its engine replaced early in its life, for example, so if you feel anything amiss don’t put it down to the newness of the car or the running in process, get it checked. But don’t be content with a simple “that’s ok” – ask why, probe a bit further, and if you don’t feel comfortable with the answer seek other expert opinions. That’s the advice you should follow.

Here’s some advice you should ignore. The first oft-cited comparison is race engines. Very often racecars are compared to roadcars, with the view that whatever’s good for the track is good for the road. Not true, and just because a newly-built race engine is taken to the track and run hard doesn’t mean to say that your roadcar engine can be treated the same way. Racecars have a team of expert mechanics constantly monitoring their every need, and the cars are rebuilt to a greater or lesser degree after every race. Not true of roadcars.

Older cars were built with more tolerance and so you had to be far less careful when running them in

The second bit of advice is for historic cars. Older cars had far greater manufacturing tolerances, so you really did have to be very careful with prolonged running-in processes. The run-in process for newer cars still exists, but is less critical to the long-term life of the car and easier – you simply don’t need to worry as much as you did 10, 20 or 30 years ago.

But, the run-in process is recommended by the manufacturers for a reason, it’s not hard or inconvenient to follow so you may as well take their advice. There’s also likely to be less issue with early warranty claims. And don’t you want to treat your new car with the respect it deserves?


Robert Pepper

Robert Pepper

Robert Pepper is a motoring journalist, offroad driver trainer and photographer interested in anything with wings, sails or wheels. He is the author of four books on offroading, and owns a modified Ford Ranger PX which he uses for offroad touring. His other car is a Toyota 86 which exists purely to drive in circles on racetracks, and that's when he isn't racing his Nissan Pulsar. Visit his website: www.l2sfbc.com or follow him on Facebook https://www.facebook.com/RobertPepperJourno/ or buy his new ebook!