I have an oil with a high soot level 159 and also high viscocity 17cst@100C, using a centrifuge we have managed to reduce the soot to 147 and the viscosity to 15,2cst@100C.

The Oil is a Mobilgard 412 that lubes a 6mW power generator.

My questions are:
1.- Is there a table comparing the soot level vs the viscosity increase??
2.- Which is an acceptable soot level??

Augusto,

It sounds like FTIR Soot values.(%Allowable)
After centrifuging Viscosity of oil is retained,
indicating oxidation byproducts is causing high
viscosity.

Soot,Oxidation,Nitration,Evaporative loss,Water
contamination,High viscosity oil added will
increase viscosity.

Trending soot data is the best way of interpretation.Changes in soot data over baseline signals combustion related problems.

Regards

Bala.

Good Day,
I'm not aware of a chart that correlates soot directly with viscosity. The problem is that there are so many other things that will also change the viscosity like Na or oxidation or water etc. If you had lots of soot and a little fuel there would be almost no change in viscosity. Anyone with sufficient data to generate this type of a chart would be reluctant to do so because it could be so easily mis-interpreted.
The internal conbustion manufactures that I am familar with normally recommend levels between 3-5% soot as being a condemning guideline. Of course less soot translates into less wear inside the engine. Running spinners on our haul truck fleet we consistently run at <1% soot.
Like the STP guy said "you can pay me now or you can pay me later."

regards........

Soot contaminatioon in in-service oils is an interesting issue in terms of its tribological performances. According to tribologists, soot, contingent on its structures and properties, may contribute accelerated wear or help mitigate wear as a solid lubricant. But as a whole, soot causes increased viscosity, filter plugging, and adsorption of detergents. Soot Meter seems an easily operatetd on-site tool for rapid soot determination with satisfactory correlation with other common lab methods, such as TGA, FTIR, Centrifugation and gravemetric method.