Hello,

Does the use of synthetic oil make the engine run smoother and quieter?

I have not used synthetic oil in my C240 before. I am thinking of switching to synthetic oil when I send my car in to dealer on the next B service.

Any advise would be appreciated. Thanks!

JOHF
2001 W203 C240X
23,700km

Synthetics are a blessing to most any engine. Some may argue that you will notice leaks outside the engine after switching. Actually if one looks closely at the dip stick upon first extraction from the engine, one will notice the oil has gravitated up the dipstick. This is because the oil is formulated to acquire a surface tension that enables it to gravitate and coat the inside of the engine. I like this 'seek out and coat' property of the synthetics. Of course, some dino oils are formulated this way, too, but the synthetics have this and a lot more going for them. This property explains why you may see leaks. On the otherhand, you can therefore be assured the inside is protected as well. I use Mobil 1 in several vehicles as well as an '81 380SL. Wal-Mart sells the 5 qt. container for 17.88.

John,

Your C240 came from the factory with Mobil One. About three or four months ago, MB announced that they will use Mobil One at their expense for all oil changes in these cars during the 50,000 mile warranty period.

I was planning on showing up for my first service with my own Mobil One for them to use, this announcement saved me the trouble and expense. I change the oil myself between their service intervals and use Mobil One at that time as well.

I would be surprised if you could tell the difference.

Have a great day,

That is incorrect. They come prefilled from the factory with a 10W-40 synthetic blend (factory special prefill). Any ACEA A3/B3 oil will due from then on (I prefer Mobil 1 15W-50). I was not aware that they now mandate Mobil 1. Only cars that come prefilled with Mobil 1 are the AMG cars.

ALSO, NEVER CHANGE FACTORY FILL UNTIL AT LEAST 4,000 MILES! It's a special fill and filter for break-in. If you do, your car may not break in until higher mileages.

I was wondering if having synthetic oil would result in quieter and smoother engine operation. You would think so... and I want to say that I have noticed a difference since using regular oil, but I think it might be psychological.

It is.

The discussion of the synthetic lubricant could be quite lengthy so let me add just a few short remarks.

Synthetic will tolerate higher temperatures without coking.
They have a more uniform molecular structure, therefore, being more true to the particular weight (30,40,50 or whathaveyou) as opposed to the dino oil which is an average of larger and smaller molecules for a given weight.
The shear strength is maintained to a higher temperature.
Also, if you need to pass an emissions test, your hydrocarbons should be lower.

If there is a down side to synthetic I do not know of it. I do know that the negatives I have heard are from those ignorant of what they speak. ;)

Negatives - $$$$$

My car sounds quiter on dino oil(Castrol 20-50)
campared to Mobil 1.15-50.Smooth operation?
No change.I prefer Castrol. I just change it
often(2500 mi.)and I change it hot.:)

Just to comment on something Dsinger said about using a ACEA A3 rated oil. There are only a couple of synthetic oils available in the USA that meet the strict European standard. Mobil 1 15W-50 is the only Mobil 1 that meets this standard. Valvoline Synpower 5W-40 is another. Castrol Syntec 5W-50 also claims to meet this standard, though there has been some debate over whether or not Syntec is a real full synthetic, but that's another subject. No oil, be it "dino" or synthetic that is below xxW-40, meets the A3 standard. Porsches come factory filled with Mobil 1 0W-40. I don't know about the factory fills of the newer Benzes, but I am willing to bet it is at least a xxW-40 oil. Again, because anything thinner does not meet the A3 rating for high performance/extended drain interval oil.

The Mobil 1 prefils are indeed 0W-40. Only some dealerships have this oil. I wish I could get my hands on some.

I just recently used the Valvoline SynPower 5W-40 and found I vastly prefer Mobil 1 15W-50. The Valvoline causes the oil pressure to be a hair low at idle for some reason. I'm not sure that's anything bad, but I don't necessarily like it.

Not Exactly The Way I Heard It...
 

My understanding was that the detergency inherent in synthetic oil has a tendency to dissolve any accumulation of carbon & sludge around gaskets and seals that provided a tighter seal until it was disolved, and along with the more efficient lubricity of the synthetic due to it's smaller molucules, it gets into spaces where the dino oil wasn't going. All of this is the sum of what may cause some engines to develop some external leaks.

According to every conversation I have had with Mercedes, their dealers, mechanics, and other technicians, ALL current models since model year 2000 come from the factory with Mobil 1 as the factory fill.

And further, "break-in periods" for engines are usually 1000 miles, and the only oil ever used is a simple 30W. This period is used to allow the piston rings and valve faces to seat against their mating surfaces. However, due to the development of technologically near-perfect computer controlled milling and lathes used in the manufacturing of these engines, there is no "break-in" period any longer.

There is an initial 1000 mile point where the dealer wants to see the car to check fluids, wiring, and components, but the next time they want to see you after that is 10,000 miles later.

So, with all due respect, it would follow that the special oil and filter you make reference to do not exist. At least I have never heard of such things. All I have been told was that all of the cars simply come with a standard oil filter and Mobil 1 in them.

As for Mobil 1 0W40, I can buy it at my local Target or K-Mart stores. There is also an excellent oil made by Lubro-Moly that is a 0W40 called "SYNTHOIL ENERGY". Ask Phil at FastLane/PartsShop if he can get it, because they already handle Lubro-Moly

For more information on synthetic oils, search the archives, and/or go to these links:

http://www.mobil.com

http://www.redlineoil.com

http://www.liqui-moly.de

As far as the post 2000 models, you may be correct, but what I heard was true until 2000.

Way to go Scott!

Only comment I would have is to express some minor concern as mentioned by one of the other writers, at using a 15-50 oil in an engine designed for very thin viscocity ... this would seem to be counter to logic.

There is little reason to continue to use non-synthetic lubricants. They are simply better.

George

Mobil 1 15W-50 works great in all engines. It works best in the older ones though (eg. M119, M110, M104 and earlier). Basically up through the 97 switchover. The newer engines work as well if not better on 10W-30 synthetic.