Today's stationary gas engines are continually challenged to deliver better efficiency and increased output. Equipment manufacturers are responding by evolving their engine designs, but operators of these next generation engines also need to adapt. Choosing the right lubricant for engine protection and following best practices to maximize oil life is essential to withstanding the severe conditions created by next generation gas engines.

From optimized combustion chambers and increased engine speeds to advanced air-fuel management with greater emission control, original engine manufacturers (OEMs) are making important improvements. However, it's critical to note that these new designs can lead to maintenance challenges if not properly managed. Understanding how these changes impact lubrication and oil life will help ensure operators can protect their new engines while continuing to get the most from their oil investment.

"Striving to achieve greater efficiency and power per given displacement, OEMs are increasing the BMEP of engines," says Clint Buhler, Technical Services Advisor for Petro-Canada Lubricants, referring to Break Mean Effective Pressure, which is an indication of operational severity and is proportional to the torque and power an engine can exert. It is calculated by averaging the cylinder pressure throughout the combustion cycle.

"As brake horsepower increases, so does thermal loading," Buhler explains. "This increased heat has a severe effect on the oil – the rate of oxidation and nitration will increase as will the rate of acid formation within the lubricating oil."

Because of the higher temperatures generated in these engines, OEMs are also using new hardware – for example, changing from aluminum to steel pistons. The latter holds onto heat much longer, which also contributes to the rise in temperature. All of this adds up to shortened oil life and decreased maintenance intervals, along with potential engine wear and durability concerns.

According to Buhler, cleanliness of the piston ring zone area is critical, particularly in engines experiencing oxidation and nitration degradation of the lube oil, as both contribute to unwanted deposit formation that can interfere with ring sealing which can lead to premature wear. This can be combated by a robust detergent additive system as found in the SENTRON product line."

However, the distress or impact of new engine severity is not uniform. The effects from increasing BMEP vary according to engine design, and the severity of the engine depends on the mode of combustion that is employed. For example, lean‐burn engines may draw in up to twice the amount of air during combustion as compared to rich-burn engines. This greater volume of air effectively cools down the peak combustion temperatures in the cylinder, which reduces nitrogen oxide (NOx) production and thermal loading, while allowing for higher BMEP. Rich-burn engines, in contrast, achieve lower emission levels via catalytic reduction, but high combustion temperatures restrict output and limit the potential BMEP, so there is a lower degree of efficiency than with lean‐burn engines operating at typical air-fuel ratios.

"The first order of business for operators of new engines is to do your homework," says Buhler. Operators need to be educated on their equipment. The very first consideration is following the OEM requirements for maintaining warranty (during the warranty period). Next, get to know your engine, how it runs and what to look for. Hindsight is also helpful; look at your fleet’s maintenance history and analyze any recurring issues and trends.

A critical step is to put a used oil monitoring program in place. According to Buhler, "Used oil analysis is key in optimizing the life of your engine as well as the life of the lubricant. The data derived from used oil analysis will empower maintenance personnel to make informed decisions. Your Lubricant Technical Services Advisors can provide guidance to end users with these programs.

Closely monitor your engine, documenting all trends, emissions readings and used oil analysis. Review the OEM manual for the recommended maintenance intervals, then work with your supplier and OEM to determine the right intervals for your fleet. Finally, take a balanced approach; make sure to account for other maintenance requirements of the equipment as well.