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post #11 of 22 (permalink) Old 11-23-2005, 03:54 PM
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RE: Oil vs synthetic

Ramp - 11/23/2005 6:22 PM

If it has been using "regular" oil I believe you must stay w/ regular oil. If you switch to Syn (Mobile 1) oil it will really screw-up you engine. MB was successfully sued several times for engine damage caused by this switch a few years ago. I believe there is an MB Bulletin out there somewhere about this.
I have studied the documents related to the law suit and the beef of the complaint was the FSS denoted oil changes every 12,000 miles but MB did not specify using synthetic oil to get this kind of life. Many owners used conventional oils instead of synthetic that resulted in engine damage, sludging and excessive oil consumption.

I had a lengthy discussion with a very competent mechanic about changing oils and he said that it would be a good thing to change to synthetic but not the other way around.

Each unto his own, I would definitely change to synthetic (Mobil 1), possibly a 10W40. The owners in the E320 forum would know more what they have had better luck with.
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post #12 of 22 (permalink) Old 11-24-2005, 08:00 AM
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RE: Oil vs synthetic

A friend of mine who is a mechanic says that if your switch to a synthetic oil after using regular oil, the engine should be flushed out. This will loosen up and get rid of sediments that build up the the nooks and crannys inside the engine.

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post #13 of 22 (permalink) Old 11-24-2005, 08:23 AM
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RE: Oil vs synthetic

This question comes up alot with people.

And the real answer is a synthetic oil is a better oil then the std mineral engine oil. Lets not get into the benefits of synthetic at this time. Lets get into some of the reason people have issues when switching to synthetic oils.

The bottom line if you wnat to read this below is

1. Synthetics will loosen,clean crud from inside your engine and also help your engine run cooler, smoother, and help produce better horsepower and respond better. But beware of the old sludge, setiment, and etc that has been in sitting your engine dragging down your engine all this time.

2. With all that loose material you may find some leaks mainly due to the fact that it was simply clogged or sealed with oil crud. Understand that you had this problem before you just simply did not know about it.

3. IF you really want to change do engine flush first then change the oil, then drive around for say 1/2 an interval while watching for problems. Then change it again (make sure you definetly change your filter again).


PS. Hi guys I am new to the forum :-P

Here is a some good info and would do a better job and take me less time to post.

"I am considering replacing the mineral oil in my engine with a synthetic oil. The engine has 50,000 miles on it. I have heard that the mineral oil and synthetic oil are compatible. Is this true?"

Generally, the reference to synthetic oil for an engine, means a lubricant is formulated with a polyalphaolefin (PAO) base oil. PAO, which is often called synthesized hydrocarbon, is pure and is compatible with mineral base oils.

However, because the PAO base oil does not dissolve additives effectively, it is usually formulated with an ester co-base (usually di-ester and/or polyol ester). The additives are soluble with the ester and the ester is soluble with the PAO.

Likewise, the PAO tends to cause seal shrinkage and the ester causes seal swelling, so the effects are offset when both base oils are present. It is the ester that can cause problems when one changes from mineral to synthetic. Ester base oil used alongside PAO base oil in lubricant formulation has excellent natural detergency. In other words, it will clean up varnish on component surfaces as a result of thermal and oxidative degradation of the lubricant. When one switches from a typical mineral-based engine oil to a typical synthetic-based oil, the varnish layer will be removed by the ester in the synthetic oil and become suspended.

This suspended material can rapidly clog filters and can block oil flow passageways and lead to component starvation. The same is true for gearboxes and other industrial machines. So think twice about switching to synthetic oils in applications where the engine or other machine has been operating for some time with mineral oils. If you decide to make the switch, try to clean the system before making the change, then monitor it carefully once you start it up.
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post #14 of 22 (permalink) Old 11-24-2005, 08:45 AM
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RE: Oil vs synthetic

My inclination is generally to run what MB says you should use in your owners manual.

That being said however, I think experience and conventional wisdom indicates that technology has probably advanced significantly since the mid-90's.

Our factory dealer and private MB provider encourage the use of synthetics and suggest no problems with a conversion but recommend that the first oil change after conversion be done early in order to flush the system of any residue.

I switched to synthetic on our 92 300SL when we got it 6 years ago- our 99SL, the E and ML all came from the factory with synthetic and we've continued the practice.


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post #15 of 22 (permalink) Old 11-24-2005, 09:22 AM
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RE: Oil vs synthetic

I was in a big hurry to switch my Maser over to synthetic - I was told that if it's been running on normal, to keep in on normal - just to change it a lot more often. He said after a rebuild, you can start over and stick with synthetic.


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post #16 of 22 (permalink) Old 11-25-2005, 01:45 PM
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RE: Oil vs synthetic

The 'benefits' of 'synthetic' engine oils are highly over-hyped in most cases. Unless you plan to run the 'synthetic' 10K miles or longer,it is more cost effective to use 'conventional' premium quality engine oils of the appropriate viscosity.

In reality, there is not a great deal of chemical difference between 'conventional' high quality base oils and 'synthetic' base oils. The most improtant difference from an automotive viewpoint is 'synthetics' have poor solvent power for additives and sludges,varnishes. This means the 'additive package' added to the base oil is significantly different and includes 'co-solvent' conventional base oils. The 'synthetic' oils WILL runlonger before beginning to oxidize--but when they do start to go--they degrade MUCH faster than conventional base oils. Also , the synthetics lack some of the natural anti-oxidant, extreme pressure anti-wear characteristics, and the additive package has to have more of those things to perform as well.

Bottom line--you HAVE to change the crankcase oil according to the type of driving AND the oil you use. Short trip, stop and go(what MOSt people drive) requires much more frequent changes, regardless of base-oil because fuel dilution and water accumlation is a major concern. Freeway cruising is easy service, and high quality 'conventional oils will easily run 6-10K and still meet original certification standards.

To me, it simply makes no sense to own a $50-100K automobile and skimp on service--including opportunities for the service techs to look and see anything out of whac whatever. Yearly oil changes with synthetic simply are poor overall economics. 4 month 4K mile change intervals are MUCH better overall for the health of the car.
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post #17 of 22 (permalink) Old 11-25-2005, 02:43 PM
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RE: Oil vs synthetic

That makes a lot of sense, but I had to laugh when you said "...synthetics lack some of the natural anti-oxidant...characteristics..." Maybe we should use vitamin E in our crankcases...?
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post #18 of 22 (permalink) Old 11-25-2005, 02:47 PM
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RE: Oil vs synthetic

Ramp - 11/25/2005 5:43 PM

That makes a lot of sense, but I had to laugh when you said "...synthetics lack some of the natural anti-oxidant...characteristics..." Maybe we should use vitamin E in our crankcases...?
Isn't lycopene an anti-oxidant?

Your write up did make sense. Makes me think of synthetic oil differently.

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post #19 of 22 (permalink) Old 11-25-2005, 06:54 PM
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RE: Oil vs synthetic

My understanding of PAO oils like Mobil One and Anzoil ( but not the other imposters) is that they have a higher vaporization point, so are far more forgiving of high transient temperatures (we never allow overheating from inattention - right?) and their shear resistanceis much higher. In addition the wash off resistance is higher.

This keeps oil on the bearings and cylinder walls longer and more effectively from sitting overnight or longer and resists the piston rings from shearing the oil film and wearing cylinder walls.

In addition, I suspect the FSS, if you have one, is set to determine oil life based on the assumption of synthetic oil use .


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post #20 of 22 (permalink) Old 11-27-2005, 12:18 PM
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RE: Oil vs synthetic

Synthetic oils are part of a comprehensive rethink of engine oil lubrication. The use of synthetics along with modern engine designs and long-life oil filters such as the fleece design result in fewer oil changes, increase engine service life, aids modern engine emission controls for less pollution, and provides better fuel economy.

This is not to say older engines can not benefit from synthetic. Older engines like mine, however, benefit from frequent changes – my 300 D had its oil changed every 3000 miles (with a new filter) and it’s almost to 400,000 miles w/o any problems, rebuilds, or compression loss. The same is true for my V8 which has high miles for a gasser and also no problems.

My M103 is a good candidate for a synthetic switchover but I keep it on dino, I may change later but for now I just can’t get out of the habit of frequent changes that served my OM617 and M117 so well.

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