Within an engine, the unwanted formation of sludge can have significant and undesirable effects. When an engine lubricant oxidizes through a combination of operating conditions, fuel quality and operating time, it degrades significantly, radically thickens and leads to the formation of a thick heavily oxidized oil known as black sludge—resulting in the engine lubricant only partially flowing around the engine and, in the worst case, not flowing at all due to blocked oil ways, leading to oil starvation and costly engine failure.

The CEC L-107-19 sludge deposit test is a key gasoline lubricant performance test within the latest ACEA Light-Duty Engine Oil Sequences upgrade. Applicable across all A/B “High SAPS” and C “Lower SAPS” categories, it is commonly referred to as the “M271 EVO” test. The M271 EVO test has been introduced into the ACEA 2021 Light-Duty Engine Oil Sequences in place of the Daimler M271 test. It replaces aging hardware with a modern and hotter operating turbocharged gasoline direct injection (TGDI) engine. Given the increased move toward TGDI engines, this test better reflects modern engine technology and the challenges facing modern high-performance engines.

While intended to be published in the ACEA 2016 upgrade, first released in December 2016, technical delays meant the M271 EVO test could only added into the third revision of the ACEA 2016 Light-Duty Engine Oil Sequences which was published in July 2020.

The purpose of the M271 EVO test is to assess sludge deposits around the engine in a TGDI engine with a fuel that is prone to generate sludge issues.

Each test uses a new 1.8 Litre Daimler M271 EVO engine incorporating a gasoline direct injection system with a single turbocharger. The sludge fuel used in this test contains 10% ethanol (E10), reflecting the increased biofuel content being used across Europe.

The M271 EVO test is conducted in two phases:

• The first phase operates for 75 hours, running the engine at high speed and high load, to oxidise the engine lubricant and promote fuel dilution into the engine lubricant.
• The second cyclic phase operates for the rest of the test with alternating speeds, loads and temperatures. The total running time of the second phase is dictated by the severity of the fuel batch used.

The key performance requirements of the M271 EVO test are the average sludge ratings from five components around the engine: the oil pan with sump, cylinder head, cylinder head front cover, valve cover and timing case cover. Lubricants meeting the requirements of ACEA 2021 Light-Duty Engine Oil Sequences must achieve ≥8.3 merits, demonstrating an acceptable level of cleanliness across the engine. Engine lubricants passing the M271 EVO test must be correctly formulated to ensure the lubricant handles differing fuel qualities, demonstrates strong oxidation performance and withstands the higher temperatures within a modern gasoline engine.

Our View

Engine lubricants meeting the M271 Black Sludge test must be correctly formulated to ensure they deliver the performance and protection demanded for today’s modern and high-powered engines.

For more information on the ACEA 2021 upgrade for light-duty engines, please contact your Lubrizol representative.