"Running In"

  laurie53 09:26 13 Apr 2008

Remember having to do that with a new car?

When did it stop, and why don't we need to do it any more?

Are manufacturing tolerances now so good that it is no longer necessary?

I know that they can now bench run engines, but what about gearboxes, wheel bearings and all the other rubbing parts?

  anskyber 09:32 13 Apr 2008

It's still there.

The last three cars I bought all came with the comment from the salesman "it's OK just drive it"

Looking at the handbook however there is always a reference to not exceeding certain (eg 3000) revs in the first 1500kms. The gearing on modern cars can frequently mean that on top gear the rev limit during "running in" is higher than the gearing required to do 70mph.

The books also say do not use full acceleration, brake hard or corner quickly as the brake pads, discs and tyres bed in.

  octal 09:33 13 Apr 2008

That's the question I asked a few years ago when I bought a new car, all they said was to drive it normally without revving the engine unnecessarily for a while. That must have been about ten years ago, but I suspect it goes further back than that when you didn't need to run cars in as such.

  Quickbeam 09:39 13 Apr 2008

Partly to do with better materials that don't glaze new cylinder bores.

Partly the new synthetic oils that don't break down before 20,000 miles.

The manufacturing tolerances now are robot/computer controlled, so any operator variance/inaccuracy between Monday mornings hangover production, through the week, peaking in quality somewhere mid to late week, and then dropping of by Friday's production, are now a thing of the past!

I believe BMWs now have a 30,000 mile service period.

  johndrew 09:54 13 Apr 2008

Any mechanical interface that is machined will have slight imperfections that will `run-in` during early usage. piston ring/bore, journal/bearing and gear meshing interfaces all need to `get used` to being in contact even in modern vehicles.

You may be able to get into a car and drive it at 70mph immediately but it may well be deterimental to the overall life of various components.

  Quickbeam 10:04 13 Apr 2008

It's not so much the 70mph, but continuous unvaried engine speeds... Still best not to thrash a new car.

  Noldi 10:24 13 Apr 2008

Its more about don’t thrash a cold engine. Even though new materials have more or less eradicated running in you should still give the car chance to warm up, let all the materials expand and the oil to reach optimal operating temp.
I think you should take it a bit easier for the first few drives, learn how the car works and to be familiar with the controls EG not knowing how the wipers operate and getting caught by sudden rain shower etc.


  Legolas 10:30 13 Apr 2008

That brought back memories, I remember as a youngster seeing a sign on the back of peoples cars informing everyone they were "running in" my father explained its meaning to me then, but it is years since I have seen it.

  Cymro. 10:44 13 Apr 2008

When I first started to drive in the early 60s we considered it good going to get 50,000 miles out of an engine before it was past its best.

These days 100,000 would be considered quite normal for an engine before any major work was necessary. But as most people who buy new cars do not expect to keep their cars for anything approaching that sort of mileage running-in is thought unnecessary.

If running-in made any difference it would be after very high millage and as the original owner will have most likely changed to another new car long before that running-in is a thing of the past and I think only necessary if you intend to keep the car for a long time or high millage.

  Bingalau 11:16 13 Apr 2008

I have always run my new cars in. Must be old habits dying hard. Mind you I only change cars every 100,000 miles or so, the one I have got at present is six years old and is no where near that mileage yet. Once I retired I find I no longer go driving all over he place. Free bus and train and ferries in our area. Bikes for short journeys. I think I will flog the old Jam Jar and just hire one when I need to go anywhere.

  Quickbeam 11:27 13 Apr 2008

"in the early 60s we considered it good going to get 50,000 miles"

I had a mid '70s Morris Marina on 80,000 miles that needed a head gasket changing. When I got the head off there was a huge wear step at the top of the cylinders, so the gasket job became a re-bore, new pistons, crank regrind, big and little ends!

I had (I don't do now) the head gasket on one of my private hire Skodas on 160,000 miles changed a few months ago, changed the gasket, bolted it back up... away we go.

"They don't make 'em like they used to"... thank god for that!

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