Changing to Synthetic - Page 3 - PeachParts Mercedes-Benz Forum

Greasy · #31 12-13-2003, 07:54 PM

how can Rotella T synthetic not be synthetic?
I have been using it in my MB Diesel for 2 years with no problems

#32 12-13-2003, 08:32 PM

Rotella synthetic (as well as MANY other oils marketed as "synthetic") is made largely from clsss III oil stock - mostly hydrocracked oil. It is inferior to and is much cheaper than true synthetic, but has some of the more desirable properties of "true" synthetics. It has substantially inferior temperature/viscosity characteristics unless considerable quantities of viscosity improvers (VIs) are added and a much higher low temp pour point (all other things being equal).

Mobil 1 oil is largely class IV (synthesized) oil with minimal VIs while Shell Rotella, and most other major oil company synthetics (Castrol, Pennzoil, Valvoline) marketed in the US are made from mostly class III base stock, but are called "synthetic" because US courts have ruled that such a subterfuge is permissible! Other full synthetics available in the US include Amsoil and Red Line - and there ARE others.

There is NOTHING wrong with using class III oil (or conventional oils either for that matter) IF THEY MEETS YOUR NEEDS, but they should be clearly identified and cost considerably less than oil that consists largely of class IV stock and is much more expensive and behaves much more nicely in VERY cold or very hot temperatures!

Marshall

#33 12-13-2003, 09:13 PM

Quote:

The problem with Mobil 1 15W-50 is that it is API CF rated oil.

Let's try this. The correct API rating for "light duty" diesel service (and ALL automobile and pickup truck diesels are "light duty" diesels) is CF rated oil! That's the CURRENT API standard - not something from the dark ages. Many CF rated oils do NOT meet either the ACEA or the Mercedes 228.x or 229.x standards so should NOT be used in Mercedes diesels, but the ACEA and Mercedes standard for light duty diesels are much different than the standards for BIG diesels. There are CF and higher (CG, CH and even CI) oils that DO meet the Mercedes standards and are thus entirely adequate.

A higher TBN is of NO advantage or benifit if increased acid neutraliztion is not required (and with 5-15kmi oil/filter change intervals and low sulfur fuels increased neutraliztion is USUALLY irrelevant). Increased soot suspension characteristics are not required and may not even be desirable if soot levels are expected to be kept below 2% even if the oil could hold more soot in suspension (as is the case with ercedes light duty diesel engines). Mercedes uses frequent oil changes to keep the soot levels below 2%.

With suitable soot filtering, Mobil 1 can be (and has been) used for 50+kmi in light duty diesel service before the TBN drops to the point where the oil needs to be replaced.

Discussions with the tribologists at Mobil over the last half dozen years have provided me with MOST of my knowledge on the subject. They first pointed out that there is NO advantage to using CG or higher rated oil for light duty diesel service. They agree that their Delvac 1 is "better" oil - having many superior characteristics - but they also point out that those characteristics will not improve the life or performance of a light duty diesel in usual applications in any measurable way - even over hundreds of thousands of miles. One of the engineers had a 123 300TD that he'd bought new and had traveled 225kmi when we talked. It had been "fed" nothing but Mobil 1 since the first oil change and he claimed that the timing chain stretch was less than 2 degrees and that valves seldom required adjustment more often than every 50-60kmi. I ask why he didn't use Delvac 1 and he insisted that it would have changed NOTHING.

Delvac 1 is a more "refined" and complex oil product and a VERY good one, but it is NOT required and offers NO detectable benifit in light duty diesel service. When I get it for the same price as Mobil 1, I use Delvac 1 (I really like the 5W40 viscosity) but when Mobil 1 is 20-30% less expensive, the Mobil 1 is entirely sufficient.

Marshall

BoostnBenz · #34 12-13-2003, 10:25 PM

My dealership would never have a deal like that, I don't like my stealership very well. I stock more parts for my 123 than they do for the 116, 123, and 126 combined (they also tend to charge more than retail). Odds are they don't even carry Delvac if they don't carry any parts for them then they must not work on them either. That is a good deal, it seems like delvac online is more like $100 for four gallons plus shipping. If the normal mobil 1 is no real different (it is intended for diesels as well) and I can get it locally and for cheaper I'd rather stick with it. That makes me feel much better that MB approves my 15w50 supersyn.

SHARK1007 · #35 12-14-2003, 08:22 AM

Marshall:

That's pretty much exactly what I was going to say, but mostly I buy Mobil 1 because I like the silver container.

engatwork · #36 12-14-2003, 08:51 AM

for diesels

#37 12-14-2003, 11:39 AM

Mr. Booth,

Still curious what those "undesireable properties" are in the CI-4 oils.

To make a long story short, CF is OK. CI-4 is better. Thats all.

stephenson · #38 12-14-2003, 12:33 PM

Punky,

I tried Rotella Syn (not really a syn, I understand) cause it was cheaper than M1 ... got a leak so switched back ... leak lessened ...

Lesson for me ... stay with lowest price, real (well, there are dissenters on this topic even with M1) synthetics ...

Thankfully, the truth is getting out on the don't switch thing ...

#39 12-14-2003, 02:22 PM

Quote:

Still curious what those "undesireable properties" are in the CI-4 oils.

It's been reported that to increase the ability to suspend higher concentrations of soot/PM and to prevent the "poisoning" of soot traps or CATs that will soon be required, some the the most effective anti-friction additives had to be reduced or excluded from at least some CI-4 oils (not all CI-4 oil use the same means to attain their ratings - which is why SOME oils are far superior to others for certain purposes even though they havbe the same API rating).

For this reason SOME manufacturers have not approved the use of API CI-4 oils as SOME of them may result in excessive engine wear when compared to older formulas. New engines will be required to tolerate the CI-4 formula. This is by NO means resolved yet. CI-4 is the first oil classification where there was really considerable discussion about backwards compatibility. Until the early '90s, newer oils were essentially superior (often FAR superior) to the oils they replaced, but since then, fuel consumption and emission requirements have combined to cause owners and manufacturers to question whether the new formulas are actually better and some warranties have been voided if the newer formulas was used in place of the originally specified blend.

Marshall

Robert W. Roe · #40 12-17-2003, 12:29 AM

I wanted to clarify one thing.
I am running 0W-40 in my M103 gas 300TE, not my diesel.
I'm thinking of using 0W-40 in the gas car in winter, 15W50 in the summer. (I can get 15W50 a bit cheaper than 0W-40)
You people *are* making me consider M1 15W-50 for my 300SD however. Eight quarts is a lot, but I just might keep the car for a while.
I noticed no major leaks with the Rotella "synthetic" (blend) so Mobil 1 just might be the ticket. Wish I could find the Delvac cheap locally though.

gsxr · #41 12-17-2003, 11:27 AM

One other thing I forgot to mention about the "fake" synthetics like SynTec an Rotella Syn. They may break down sooner and cause artifically increased oil consumption rates. I believe Marshall experienced this (??) where an engine would start burning SynTec after 4-5kmi, yet the same engine would not do that when fed M-1. If I'm getting the story wrong, feel free to correct me, Marshall!

JHZR2 · #42 12-17-2003, 11:38 AM

I poured delvac 1 into my 83 300D at 198k or so, and have been running a mix since. Didnt notice any mpg difference between 100% synth and 50/50, but did get less mpg with straight dino.

Delvac 1 is the best synth you can get. M1 15w-50 (maybe with a bit of 0w-40 mixed in in the winters) works well also, but on an OM617 engine, id say one way or another to change at ~4000mi, as they put more soot into the oil.

JMH

#43 12-17-2003, 07:18 PM

JHZR2 said,

"on an OM617 engine, id say one way or another to change at ~4000mi, as they put more soot into the oil."

Just one of the reasons you want a CI-4 rated oil. Its just better, no question.

JHZR2 · #44 12-17-2003, 07:43 PM

I dunno about that... the API spec didnt really change the soot loading capacity of thequality oils... D1 held ~4% when CH-4 as well.

The key to me is soot handling... And I know when soot gets above about 2%, you can feel a response from the oil. Shear thickening sets in, because the dispersing action of the oil additives can only do so much. It is not a binary tipe behavior, there is a period at which the viscosity change is negligible, then some range where the oil shear thickens slightly, then it shear thickens a lot, and then beyond there (at or above the soot loading range), the soot is not necessarily fully suspended, and will damage, as it will be abrasive.
In big trucks the bypass is large and very fine,and the oil amount is such that the soot stays suspended and at low percentages for much longer, simply by dilution.

But soot is soot, and the oil will start to thicken the second soot starts to touch it. its just a matter of when itll be significant.

I have found 2% will not influence economy particularly, but will effect by butt-o-dynometer, and plus many dino diesel oils top at about 2% loads +/-.

The reason I like CI 4 is because it takes the thermal and eneral shock that an egr system puts on the oil. our engines were egr equipped before, and that is tough on diesel oil.

But one way or another, the actual final proof is oil analysis... if after 4000 miles you have 1-1.5% soot and 20ppm of iron or less, with no Na or K, youre doing really well, and cant ask for more.
And if you can get that with an API SD oil, then so be it (you can, youll just be changing it every few miles

gsxr · #45 12-17-2003, 08:13 PM

Quote:

Originally posted by oilburninokie
JHZR2 said,

Just one of the reasons you want a CI-4 rated oil. Its just better, no question.

I don't think you read what Marshall wrote. Just because it's a newer rating, does not mean it's a BETTER rating! If the additive packages were compromised to pacify emissions regulations, or for other reasons, the older spec would be preferable for most of us with older engines.