Passenger car engine oils remain a vital component for both the internal combustion engine and aftertreatment system, with Original Equipment Manufacturers (OEMs) investing considerable resources to ensure that lubricants deliver the required levels of efficiency and hardware protection. Often, some minor engine issues can actually be oil derived, including oil leaks, poor engine operation and higher fuel consumption. More significant problems can include corrosion, lack or loss of lubrication, loss of engine cleanliness and even engine failure.

Manufacturers and the lubricant industry have developed testing to guarantee these problems do not occur and vehicles remain protected throughout their lifetime, but for consumers, identifying the best product is not always easy in today’s service-fill market. Consumers are presented with products that are ‘Approved’ to an OEM specification, meaning industry tests have been undertaken and passed, as well as alternatives marketed as ‘Suitable for Use’ (SFU) or ’Meets’ an OEM specification – which are essentially unapproved alternatives.

We sourced a range of off-the-shelf engine oils claiming to be SFU premium OEMs and tested them in key baseline bench tests to evaluate their performance. The results showed that 80% of the SFU engine oils failed even the most basic of performance parameters, with 50% showing a major test failure.

Corrosion testing was conducted to understand how well protected engines in the field might actually be. OEM specifications often state zero levels of corrosion; however, analysis showed high levels from a number of the off-the-shelf fluids tested.

Results of corrosion testing: Grade 1 result from an OEM-approved engine oil (left). Grade 5 result from SFU engine oil (right)

Poor cold flow performance, particularly in areas where ambient temperatures often go below 0°C, has been noted as a cause of field failure in the past, with oils forming a gel or simply not flowing and therefore leading to oil starvation. Tests were introduced to mitigate these performance issues and the study showed that some engine oils demonstrated extremely poor low temperature pumpability.

Engine seals are critical in keeping oil within an engine and avoiding costly leaks and subsequent oil top-ups. However, our testing once again highlighted that several SFU lubricants achieved poor results, including an elastomer seal physically cracking.

A key deposit test for gasoline engines observed a notable increase in deposits, up to 131% above the industry limits, compared with 80% under the industry limit for the OEM-approved lubricant tested. In this situation, lack of performance could seriously impact engine operation, which could lead to a costly engine failure. 

While OEM-approved engine lubricants provide protection against hardware issues and mitigate the risk to performance, our research showed that the use of unapproved SFU engine lubricants could be likened to flipping a coin, with many lubricants that claim suitability to an OEM specification demonstrating a major test failure. Such findings have potentially serious consequences throughout the supply chain. For end users, the use of inferior-quality fluids can result in costly engine damage and potential loss of trust in their service workshop. For manufacturers, engine failures caused by inferior, non-approved engine fluids could negatively affect brand reputation among end users who mistakenly attribute this to poor engine hardware reliability. For oil marketers, all aspects of liability lie with the finished fluid supplier, including the cost and the legal liability for any failure, investigations and complaints. Therefore, the commercial decision to market SFU engine oils should be supported by verifiable performance testing results relevant to the OEM specification limits. 

Our View

Additive companies, have an equally vital role in ensuring correctly formulated additive systems have undergone robust testing against the OEM’s specification requirements, enabling oil marketing partners to correctly promote the engine lubricant’s technical performance to customers. Research highlights the need for awareness of the risks and issues being witnessed in the market, as well as a need for debate and action within the industry. 

(Content pulled from original article in Engine + Powertrain Technology International.)