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Engine Oils , SAPS, HTHS

Posted: Thu Oct 02, 2014 1:35 pm
by JBT
Some useful info from the Motul website.

What is SAPS and HTHS?

SAPS stands for Sulphated Ash, Phosphorus, Sulphur. All of which are naturally occurring elements in fluids refined from crude oil such as engine oil and diesel fuel.
There is currently a focus to remove these elements from oil and diesel fuel to reduce hazardous emissions and improve fuel economy.
When SAPS enter the combustion cycle on diesel engines, the particles leaving the exhaust will block up DPF’s (Diesel Particulate Filters – think of it as an air filter on your exhaust) and CRT (Continuously Regenerating Technology – similar to DPF but it works continuously). The reason for these filters on your exhaust is to capture the black soot and burn it off.
The down side is that SAPS are also antiwear additives, corrosion inhibitors and detergents. New additives are being developed every year to replace SAPS and provide an environmentally friendly lubricant and fuel.


HTHS is a standard test method for measuring viscosity of new and used engine oils at High Temperature and High Shear by a Tapered Bearing Simulator Viscometer at 150°C.
Oils with low HTHS provide improved fuel economy but sacrifice engine protection.
Low HTHS = 2.9-3.5
Oils with a high HTHS provide engine protection over fuel economy.
High HTHS = 3.5 and Above

It pays to read the Technical Data Sheet for oils that you use to ensure that you are getting the protection you need for your application.