Common sense should tell you need to use the finest oil available if you want your engine to last :D

~Nautilus

cgranju - It's a good question. Some good points made here.

I think they are both good engines, the key is maintenance. How have they been serviced? If you find an M112 that has had frequent oil changes, either more than stipulated by FSS or at least on par, and has also used ONLY approved synthetic oil, it should prove a fine engine. I would not purchase one without this service record documentation in hand.

There seem to be quite a few ML owners with M112s that use oil, and have been serviced well. So it does seem that some of these engines use oil, whereas this was not an issue with the M104. Definitely something to consider. As stated, my M113 uses oil and it is a frustrating issue to try and rectify as diagnosis is very difficult - short of tearing the entire engine open.

However, the 722.6 transmission is leagues beyond the old 4-speed in terms of performance and quality of ride. If you bought a 1999 model, you would probably be in good stead in terms of getting a solid specimen.

Then there is the 1997 E320, which will give you the M104 and the 722.6. A family member here has this car and it has proved very reliable and durable. Now close to 160,000 Km, it has the original tranny and engine. Not a single problem with either (doesn't burn a drop of oil either). We have had the transmission fluid changed however, and will do so every 50,000 Km - Mercedes' 'lifetime' fill be damned.

Good luck!

At this point I think condition, mileage, and service records are of greater significance than which engine is chosen. I currently own one of each - a 1993 300E 2.8 and a 2001 E320 wagon. In normal driving they are almost indistiguishable - perfectly smooth, responsive, and quiet. Add a bit of throttle and they both get aggressive, pulling hard at upper RPMs with a sporting growl. Different notes, of course, an I6 doesn't sound like a V6.

In terms of repairs, the M104 has required both a head gasket and engine wiring harness prior to 100K miles. As I understand it, the engine wiring harness is not a concern in a 96/97 model year car.

The M112 hasn't needed any repairs. Of course, it's only 7 years/55K miles old.

The professional techs on the site do report occasionally reringing the M112/M113 V6/V8 engines. So far I haven't seen any data points that correlate, or not, this failure with use of conventional oils. I don't know whether this failure occurs to the unlucky or only those that don't follow proper maintenance procedures. I can recall 2 occurances of folks on this site that needed new rings.

The 722.6 five speed automatic is a nicer driving transmission than the earlier four speed. It has a better selection of gear ranges, and is more cooperative in choosing the correct gear. It delivers better fuel mileage because it has an overdrive top gear and a lockup torque converter. But unless you can afford a late 99 or 2000 model year, when all the updates were incorporated, I wouldn't recommend it over the earlier transmission.

My long and rambling $.02,

- JimY

But you're missing the point. The really long lived MB engines of the past never saw a drop of synthetic oil. The point is the engines have changed. I believe MB boasted to Wall Street that they had cut nearly half of the production cost of the 112 engine family versus the prior engines. Whether they did this intentional to shorten engine life (planned obsolescence) or simply missed a calculation and screwed up is not as important as the fact (obvious to me) that it happened. Bottom end engine problems are not a laughing matter in this day and age. 104 motors and 119 motors don't have them short of really serious abuse.

Jim - great post and I agree with all of it. While I haven't seen any directly correlating data on your point above, the successful lawsuit against Mercedes in the USA by O'Keefe was based on this exact premise. That 1998-2000 MY Mercedes exhibiting oil consumption issues, and that followed FSS intervals yet used mineral oil, were to be repaired under warranty by Mercedes. The issue of course was that Mercedes failed to specify the TYPE of oil to be used in North American cars. The European standards were higher (still are) and hence the cars were already using synthetic overseas. Here in North America, the dealers used regular oil or blends and then ran the engines to the full FSS interval.

It doesn't take much engineering or biochemical knowledge to know that an oil designed to run a maximum of around 5,000 miles shouldn't be run to 10,000 miles or over. Hence the damage, and hence the oil consumption.

My car had intervals of over 17,000 Km on conventional oil. This up to about 80,000 Km or so. I don't think it is a coincidence that my engine is now consuming oil. Whether from sludge or permature wear due to the oil not being able to lubricate properly is something I may never know. No help from MB Canada either, no lawsuit up here and my car is now over the 10-year mark.

deanyel - I think the issue is not the engine construction, but the recommended service intervals that were inherent to these models. Many savvy owners ran synthetic from the start - and the fact is that synthetics WILL outlast conventional oils - and many also did an extra oil change in between the 'recommended' intervals.

It is my guess that if you ran an M112/M113 engine on conventional oil AND changed it accordingly - i.e. every 4,000 miles or so, the engine would prove every bit as durable as the M104/M119s of the past.

The engines themselves don't "need" synthetic oils, it is the FSS system that requires synthetic oil's long-term performance in order to meet the extended service interval timelines.

Just my $0.02.

I think everybody ( but you ) knows, an inline 6 cylinder engine is much more expensive to build than a V - 6 engine.
The cost & packaging have prompted most manufacturers ( BMW being one exeption ) to switch to the V - 6 engine.

Manny-

Why is an I6 engine more expensive to build?

If it is, is this a good thing? How so?

Are the parts more expensive? The labor involved?

The whole process is more expensive ( from engine block casting, to crankshaft, etc ).
As well as, a V - 6 engine can be machined on the same " line " as a V - 8 engine, which also streamlines the procedure.;)

Regardless the cost savings was also 113 versus 119 - both V8s. 104 motors and 119 motors are not particularly sensitive to oil change intervals. The 112 motors were in court in less than 4 years from their introduction, a truly stunning feat of shoddiness, and Mercedes folded like a cheap suit. The only cars out of warranty were those with more than 50k miles. I think 112/113 owners are in denial.

The whole process is more expensive ( from engine block casting, to crankshaft, etc ).

Ok, how so? Why? Looking for specifics here. For example, how is casting two heads cheaper than one?

As well as, a V - 6 engine can be machined on the same " line " as a V - 8 engine, which also streamlines the procedure.

The old sixes were the same as the 4 cylinder engines. Look at a 102 and a 103 motor. Same thing, different # of cylinders. Same for 104 and 111 motors. And 601/602/603 motors. And 616/617 motors. This modular design is NOT new.

My understanding is that MB went with the V6 for two reasons:

1. a V6 is shorter in length, allowing it to be into smaller cars

2. It is basically a V8 with two cylinders cut-off, allowing them to use the same line that makes the V8, thus being cheaper to build.

I remembered reading an old post that Larry Bible contributed on the construction of these M112 / M113 engines:

"My MB Tech friend called the other day to tell me that he had one of these new high tech engines apart if I would like to come by and see it. I made the time.

The engine was actually the v8 version, but everything is virtually the same except for the extra two holes. The car had been in a wreck which busted the oil filter housning and it lost just enough oil to cause some lower end problems.

This engine is an absolute engineering masterpiece.

Starting at the top, the rocker arm/cam followers look like something from a high buck race car. Roller followers and solid alloy construction. They're offset which makes them look even more exotic. The offset is necessary because of the three valve arrangement, there would be no other way to fit them all under the valve cover.

The liners are some sort of exotic alloy. They have a tan look to them, and after 50,000 miles, you couldn't tell that a ring had touched them. They are fit into the block such that there is plenty of cooling liquid all the way around them, something that would not be exposed with the head off of most engines.

The rods are very interesting. They forge and machine the rods, then break them at the parting line. I'm not sure of the reason. I can see where it could eliminate some machining steps, but I can also see that this would make for a more precise fit.

The main bearing caps and webs are really great. There are four vertical bolts and THEY'RE CROSS BOLTED. This is a racing engine feature. The only other engine that I've ever seen apart that used this technique for incredible bottom end strength was the 427 Ford of the mid sixties. I was told that MB actually started doing this with racing engines in 1948.

I missed the pistons. They have almost no skirt at all. The story on this is that the dual spark plugs which are fired about 40 degrees of crank rotation apart, if I remember this correctly, have minimal rocking allowing for the no skirt design.

The ring package is very low tension, this evidently works together with the alloy liners, the piston configuration and the dual spark plug usage.

As I said before this engine is an absolute masterpiece. It wasn't very long ago, when this technology would have been the makings of a very nice Formula One engine.

Well for those who may be interested, there it is. It was well worth the trip and the time out of my day to see it. Now, I just hope that's the last time I see inside of one for many years. Since mine will be given a steady diet of Mobil One frequently, I hope to keep it off the engine stand for many years."

The entire thread is here:

http://www.peachparts.com/shopforum/showthread.php?threadid=1582&highlight=engine

I had also thought that the introduction of the ML was a big part of the reason. The I6 engine would've been too long to fit under the hood. Since MB wanted a piece of the lucrative SUV market, they went with an engine redesign that would fit any chassis. They use the M112/113 in everything they make, with the exception of A and B series cars.

The V6 also help improve aerodynamics. With the facelift of the W210 chassis in 2000, the hood is redesigned to take advantage of the shorter engine, lowering the drag coefficient.