How does soot effect extended drain?

[Hubjeep]

I have recently acquired a 1986 Mercedes 190D 2.5 (122k miles). My first change was with Rotella-T conventional 15w40 oil a month ago.

I am hesitant to run synthetic (as I do in the gassers) in the diesel since the oil gets black so quickly; how does this soot affect the oil’s performance.

I am basically thinking if it would be better to have cleaner dino in for 3,000 miles or synthetic in for about 5,000.

I could run Mobil 1 Truck and SUV or Rotella T “synthetic” 5W-40.

Thanks,
John

 

[Ken2]

As long as the soot does not agglomerate into abrasive particles, and as long as the soot doesn not exceed the amount there the oil thickens excessively, it is not a problem.

I've run industrial diesel engines where the oil gets black in the first hour, and I've never changed the oil until the analysis says to. It is always black, and good for many, many hours.

The engines that have soot problems are the 2002+ truck engines with exhaust gas recirculation. I haven't been in touch for a couple of years, but those were needing oil changes after maybe 12,000 miles, when 20,000 would have been the norm. The new rating, CI-4 Plus, was developed for better soot handling.

So, go ahead with the synthetic and shoot for 10,000 mile ODI with an analysis at 5000. One or two analyses is probably all you need to find what your engine likes, and what lets you sleep well.


Ken

 

[JHZR2]

black is basically irrelevant. In our 83 OM617 W123 chassis 300D, 4000 miles would still be under 1% soot, though the oil was like black ink!

In our 96 w210 OM603 (I think) E300D, 7500 miles puts us at under 0.5% soot loading, though the oil is like black ink.

Daimler engineers determined way back when that in their diesel engines, wear was minimal until ~2% soot loading. Beyond that, wear increased dramatically. I'm sure that unless there is something wrondg with your car, which I doubt, that in a 7500 mile drain of Mobil 1 Truck and SUV/delcac 1, youll have very low soot loading, regardless of the color of the oil!

I believe Mobil 1 Truck and SUV / Delvac 1 has adequate dispersants to suspend ~4% soot!

JMH

P.S. My 83 MB turbodiesel has an EGR and never showed an issue realted to it!

 

[tdi-rick]

as everyone has said, black oil does not mean much.
Our Nissan Patrol's oil is black in the first 500-1000km after an oil change, yet I can safely exceed a 20,000km OCI using Delvac 1.

UOA is here (soot is under 1% @ 20,000km, indirect injection engine) http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=26;t=000229

 

[Doug Hillary]

Hi,
Ken2, JHZR2 - I concur with your comments

Various engine/oil manufacturer's set limits for soot and once this is known a used oil analysis (never oil colour) is the best determining factor. An interim "blotter" test is also comforting for some

In my case and in well utilised engines I use 3.5% as my uptake limit and have done so for millions of kms over many years. The engine manufacturer's limit is 3% and the Oil Company's limit is 3.5%. My highest number has been 7.8% (inadvertantly & with Castrol semi-synthetic 15w40) and we often go to 4% with Delvac 1 if all other indicators (viscosity, PQ Index and iron) are OK via used oil analysis
A by-pass centrifuge seperator helps a lot with soot control and is much better than an element type by-pass device in this regard

Some oils certainly handle soot (and viscosity integrity) much better than others and in my case Delvac 1 5w-40 has proven to be a truely excellent product. That is the prime reason why I have used it for so long!
The Delvac range of oils has been well known for their soot handling ability for several decades and certainly since the 1960s

Some engine lubricants become more viscous quite quickly due to the way they control soot uptake - these should be avoided at all cost. This causes most lubricant problems in diesel engines other than coolant ingress. Some related problems are filter clogging and undesirable engine deposits in specific areas

JHZR2 - in my OM662 (5cyl, TIDI - EGR) engine I will use the 3.5%, the same maximum as I have used in light Japanese engines for a decade or so with success

A conversation many years ago with both Mobil Engineers and the additive supplier's Chemists indicated that trials with Delvac 1 had shown very little wear variances at up to 7%. They set a 3.5% limit!

ACEA test for viscosity increase to 4.8% (Cummins M11 test, this engine was a soot demon) (pending to 6% - CEC-L-093) and to 4.5% for cam pad wear(E4,6,7)

I would expect these limits will be raised in some engine families within 12 months or so when using prescribed and Manufacturer Approved and Listed lubricants. The first "cabs off the rank" will probably be MAN & MTU-Mercedes Benz

Doug

[ October 17, 2005, 05:29 PM: Message edited by: Doug Hillary ]

 

[mettech]

Run some Auto-Rx through it.

 

[Hubjeep]

Thanks for the replies!

I am glad to hear the ink black color does not always equate to excessive soot.

Next change will be with Mobil 1 Truck and SUV (especially since it is not much more money than the Rotella-T "synthetic").

Who do you suggest for testing the oil?

Thanks,
John