Evenmb

I'll be taking possession of my new car pretty soon. And coincidentally I have a road trip planned where I'll be driving up a mountain side resort soon after. The resort is not really that high though, probably around 2000m? and with a good network of road.

My concern is whether it's alright to put the C Class through such a pace during this so-called running-in period. The online manual I read say something like take it easy for the first 1500km and drive at varying engine speed.

Should I be concerned? Will it have a negative effect on the engine later on? This is my first Merc btw.

Thanks for any advice.

Glyn M Ruck

It will have no negative effect. Don't lug the engine, rather change down. Watch your temperature gauge. If the temperature climbs excessively back off. Refrain from hours at constant throttle.

While some care is sensible these engines don't respond well to being over babied. The MOS2 coated rings on an Alusil bore take quite some breaking in. Do not change the running in oil early.

Enjoy!

Evenmb

Thanks for the advice. But I don't really understand "Don't lug the engine, rather change down". Sorry for being such a noob. I am not really a driving enthusiast (hopefully that will change with my new car..lol)

So should I just leave it on Auto going uphill or paddle-shift my way up?

Glyn M Ruck

Lug = Don't put your foot down hard at low RPM. Rather change down & let the engine rev but obviously not to peak RPM.

i.e don't make high torque, low RPM demands of the engine. Equally do not use peak RPM.

Always drive moderately until the engine is fully warmed up & all clearances have normalised.

mihaelb

So given what you said about the long break-in for the Alusil rings, how long would you say the break-in period for the C300/C400 to be?

thx!

c4004matic

Agree completely. Most agree that the best break-in is one that simply varies engine speed. For example doing all your break-in at a steady 75mph is not the best. Also avoid jack rabbit starts and panic stopping since brakes need a few hundred miles to "seat" appropriately too.
Simply drive "normally" for the first few hundred miles. Strict break-in is really a thing from the past when manufacturing tolerances were larger by a factor of ten or more.

Glyn M Ruck

Take it easy for the first 1000 miles/1600 Km's & then make full use of the power & rev range. The engine will take the first 10,000Km at least to fully loosen up. Sometimes more.

Evenmb

Thanks for your explanations. That mountainside resort, although not a long trip, has some steep gradients in some areas. In those cases, I would have to "lug" the car. I guess this is my worry. Whether it's ok to do this kind of driving during the run-in period.

Glyn M Ruck

You won't have to lug the car. Just change down manually & use higher revs. The Auto box will not really allow you to lug the engine but as Benz has endeavoured to minimise fuel consumption the mapping sometimes allows revs to drop a bit low before triggering a downchange.

JT25

I was told to drive it normally from day 1. I've been switching between manual paddle and auto and all different agility settings. I've not been hanging on redline but taken it up there a few times. Turbo seemed to free up after the first 100 but perhaps that was me just getting used to the torque sweet spot

Evenmb

Thanks everyone for the input. When I took delivery, my dealer told me the same thing, no worries on hill climb and just drive normally. Just don't push it too hard till redline (or as I've learned the term, "lug the engine")

Glyn M Ruck

Enjoy!