Should synth oil be used before "breaking in" an engine?

[Ken C]

Everyone who has an interest in synthetic oil has heard that it should NOT be used until the engine is broken in (or else the engine, because of the oil's superior lubrication, will never break in properly). However, we have all, lately, also heard that MB (and other manufacturers such as Porsche, GM on their Corvettes, etc.) has started delivering their new cars with a factory fill of synthetic oil (e.g., Mobil 1).
I've used synthetics for over 25 years, but always after a generous break-in period.
What is the best procedure? I'm starting to have an old engine (M110), on a used car I recently bought, rebuilt (including honed cylinder walls and new pistons, cams, etc.), and planned to start in off (during break in) on regular oil, switching to synthetic oil later. Now I'm wondering if I should start the "new" engine on synthetic oil right away -- any comments?

Why don't you get the special break-in oil from the dealer, if you can? Break-in takes usually about 10,000miles and natural stock based oil will not hurt during, the break-in. Don't know about synthetic. The new cars come from the dealer are already broken-in so, it is no wonder they put Mobil 1 oil when, from the dealer new. Mobil sponsers MB racing teams and probably gives the oil at huge discount to the company.

[longston]

My local independent MB garage suggests a simple non-detregent oil for the first 1000 miles, then you could change to synthetic if you choose. That will be sufficient for "Break-In".

The service manager at my local MB dealer says that they used to have a 1000 mile initial "break-in" period after which they would do a valve adjustment and 1st oil change.

He said he has had no information from the factory about the new engines being specially prepared, or "broken in" at all. These new cars come from the factory with Mobil 1 in the crankcase, and do not get their first scheduled oil change for 10,000 miles. He added that they recently got a service bulletin from Mercedes directing them to only use Mobil 1 on all cars that come in for service from now on...

His thoughts on breaking in your rebuild were the same at the independent garage, and added that a rebuild needed to be treated as it would have been originally, because the rebuild wouldn't be representative of the closer tolerances that the newer engines are being built to.

[Edited by longston on 01-31-2001 at 12:33 PM]

[Benzmac]

Breaking in with synthetic is OK.!@!!!!! In fact, if I bought a new one, that is all I would run, for I don't like the thought of crosscontamination. I think you should run on the same oil all of the time.

I built the enigne on my 16v and used ONLY Mobile One. I broke it in on it and changed it after 1K miles. It is now running fine with no oil consumption.

[longston]

As if the "Benzmac" needed my approval and/or validation...

But I did just finish asking a tech on the Mobil techline the question today, and he said JUST what Donnie did!

And Donnie, should we run DelVac 1 instead of the regular Mobil 1 in our diesels? Larry Bible said that it just might be the perfect diesel engine oil! I'd like to know what's your opinion?

I think that "break in" is very close to something of the past, especially in a new Benz engine. The fabulous materials, precision machining and everything else is so far superior to engines of even twenty years ago, that there's not much of a need for a "break in" period. If you're one to abuse an engine, you might hold off for the first thousand miles or so before abusing it. If you drive an engine with care, no lugging or overspeeding, just drive the thing.

Had I not been buried in everything else at the time, I would have probably driven my C Class home and put Mobil One in it right away. I didn't have a chance for about 4,000 miles. Oh well....... From now on, it will get some fresh Mobil One about every 5,000 miles, with a hot, overnight drain when I do it, and a topsider when the dealer does it. Actually my friend, who is my dealer tech, told me he would drain it out the bottom for me if I wanted him to. I kind of doubt that he'll drain it overnight though. I'm not worried though, he can topside it, and I will still have a thorough, hot, overnight drain every other time.

Changing oil early on the first change is a great idea because there will be a small amount of microscopic particulate and even lint from rags.

The reference to "break in" oil is another thing that is probably as attainable as a Model T ignition coil. It may be out there some where, but I doubt anyone could locate it.

I expect that it is not uncommon at all to see crosshatch on the cylinder wall of a 150,000 mile MB engine. Take care of it, don't abuse it and enjoy it.

Have a great day,

[Mike Michalek]

Larry

Just for discussion sake. Your statement about better machining and materials of twenty years ago. I would think the machining specs. would still be within tolerances. The materials, cast iron and aluminum have they really changed? Do you think the oils have improve to a point that there is not as much engine wear at break in now?

Take Care
Mike

[longston]

Just to offer what I know, and certainly not to try to answer a question in lieu of, or for Larry Bible.

Mike,

Lubrication in general has become much more advanced than it was even 10 years ago. The "new" synthetics, like Mobil 1, are well beyond where they ever were. Mobil 1 actually has a new formulation that is based upon three synthetic base polymers, hence the "Tri-Synthetic" name. I recommend you check out: http://www.mobil.com for more information. You could also go to: http://www.castrol.com, http://www.valvoline.com, http://www.havoline.com, and http://www.redline.com just for starters. I, for one, have learned a lot. Both from going to their websites, and from participating in this forum.

As for tolerances, even the term itself is no longer appropriate. Tolerance indicates allowable deviation, or margins for error, and with the exact and precise computerized milling machines that Mercedes now uses, there is no need for tolerance. When you add to that, the continued advances in metallurgy (also thanks to computers), then you will find that the alloys and other metals being used in manufacturing the engines really are quite different than ever before.

When you also consider the other advances in not only automotive ignitions, fuel metering and delivery systems, cooling systems, and emissions controls, but also in the computerization of those systems, you will find that it adds to the overall "cleanliness" of the interior of those motors to such a degree, that the first oil change is recommended by Mercedes at an unheard of before now, 10,000 miles!

All of the "new" advanced lubricants, and coolants will also safely allow for a dramatic increase in their own change intervals, even in older vehicles made before that technology became available.

Unless, of course, you choose to "change it hot, and change it (more) often"...

[Edited by longston on 01-31-2001 at 10:37 PM]

[dakota]

As Larry (and others) have said, the break in period is a thing of the past to a great extent. If you look at the bearings (main, con rod, cam) etc, the better your oil, the better any initial imperfection can be handled. Cam lobes are either OK or ruined, primarily in the first couple of minutes of running...if the factory didn't lube them right for initial run, they will most likely be toast in a few thousand miles. The major components, that in the past, required sensitive break in procedures were the ring faces, ie, where they contacted the cylinder wall. In the past, the manufacturing process for rings had a hard time creating the ring in its relaxed configuration so that it was perfect in its compressed configuration while in operation in the cylinder. New technology allows them to accurately predict the correct shape...that's why the cylinder wall can be so much smoother now than in the past....the ring doesn't require the final "lapping" process (the break-in period) to ensure the perfect fit as it once did. Another thing to think about...rings receive very little lubrication, especially the compression (top) ring...I want the very best oil I can get there, and that's synthetic oil.

Mike,

I think longston and dakota have already answered your question better than I could have.

I will correct myself, as longston pointed out, tolerance is not exactly correct, so I will use the word precision. All of the fitted parts are made to much more precise dimensions.

As for materials, an example is the cylinder material in the M112 engine, the new V6 and its sister that has two extra cylinders. These cylinders are an alloy that is somehow used with the aluminum cylinder block. I saw one of these engines apart at 50,000 miles, it was apart because of an accident puncturing the oil filter cannister. These cylinders had the sharpest, freshest looking crosshatch you could imagine and very little deposits at the "ridge". These engines use a low tension ring that is sealed immediately.

Also, these engines have roller cam followers. As was very well put by one of these gentlemen, the cam and lifters are critical during start up. Most aftermarket camgrinders recommend proper assembly lube and the first twenty minutes not letting the RPM fall below about 2,000. If you get past that, you're in great shape. With the roller cams in these engines, you could probably not even lube the camshaft at startup and it would get enough splash quick enough that no harm would be caused. I'm sure you won't find ANYONE willing to test this theory, however.

As longston said the additive package in modern oils is far beyond anything we had as recent as twenty years ago.

All this adds up to an engine that for all practical purposes just doesn't require break in.

My $0.02,

[Edited by LarryBible on 02-01-2001 at 07:37 AM]

[Mike Michalek]

Scott, Steve & Larry

Thanks for all the insight. It all makes sense.

Thanks Again.