Test equipment

Wilks Infracal Sootmeter

Sample size

20ml (recommended), 5ml (minimum)


Astm D7686


% Soot

Test methodology

IR % Soot Content measures the amount of soot present in the oil sample on a scratch-resistant cubic zirconia attenuated total reflectance (ATR) sample plate.

Notes (application)

Soot is generated during the combustion process and it is usually 98% of carbon by weight.  Soot particles are near spherical in shape and tend to aggregate to larger particles.

An increased amount of soot will strain and reduce the lubricant's dispersant additive. Once it is depleted, dispersancy is lost, leaving the machine at risk. High levels of soot will cause loss of anti-wear performance, sludge formation, and increase lubricant viscosity.

Suitable for systems

Diesel engines