soot vs. synthetic

[W123126]

Just found this forum and although I don't have a chemisty backround I find the information (that which I comprehend) to interesting and very useful.

My question is....I would like to convert my (2) MB diesels ('83 CDT & '87 SDL) from conventional to synthetic oil. I believe synthetic would afford me extended oil change intervals but I'm concerned about it's ability to suspend soot succesfully over a 6k - 10k change interval. I presently change the conventional & filter @ 3k. Is the soot suspention capability of snthetic superior to that of conventional? Historically, MB diesels can go 500k without major engine rebuilds....I don't want to jepordize my engine for merely the convenience of extending oil change intervals.

 

[Bio-T]

The soot carrying capabilites of either syn or dino are essentially the same. And you are correct in that MB do seem to like to produce that byproduct. Living where you do, I would recommend a 15W40 Schaeffers semi-syn as it has a -41 pour point and will give you excellent starting in the cold and great protection in the summer. Run the first oil change to 4K and have it analyized and change accordingly. You will get as many miles out of a semi-syn as you will a synthetic without a bypass filter, excluding any factory ones.
IMHO

 

[Jim]

I run Petro Canada 5W40 synthetic in my 240D for 10,000 miles. The oil has 6% soot at the end but still very low wear metals. 1PPM chrome and only 33PPM iron. In 10,000 miles the added fuel mileage pays for the oil. My mileage jumped from 32 to 34 average when I switched to synthetic.
I am now running series 7000 oil to see how it compares.

 

[W123126]

Thanks Guys,

I very much appreciate your input.

 

[Jimbo]

They must put a lot of extra dispersant additive in synthetic in order to handle the soot. PAO molecules have little natural ability to suspend contaminants. Dino base oils are actually much better for that.

A semi-synthetic or a group III "synthetic" is probably a better choice for diesels.

 

[MolaKule]

Schaeffer's #700 15W40, Amsoil 15W40 AME, or Delvac 1 all contain HD Detergent/Dispersant packages for Diesels.

You will find that many of these oils contain extra Barium to enhance soot dispersancy.