Diesel engines have changed significantly in recent years, with today's engines running more efficiently and able to generate more power. Many of these modern engines use high pressure, common-rail injection systems that improve combustion efficiency and advanced turbocharger technology to increase power. In addition, diesel particulate filters and selective catalytic reduction help decrease or prevent emissions of harmful oxides of nitrogen or NOx and particulate matter.

These important changes to design and engine hardware resulted in the development of the current API CK-4 diesel engine oil standard. This robust standard requires that diesel engine oils manage more heat and stress while maintaining strong engine protection. They also need to deliver oxidation resistance, aeration control, wear protection and more.

An important element for Shell Rotella heavy duty diesel engine oils to meet or exceed the API CK-4 engine oil standard requirements is the additive package. It represents 15 to 25 percent of a gallon of oil with the balance being high-quality base oil. Additive packages play a crucial role in helping to keep an engine clean and protected from varnish and sludge, as well as provide wear protection and protection from heat and acids.

Key additive terminology 101:

  • Anti-oxidants - Engine oils react with oxygen in the air forming organic acids. Oxidation can cause an increase in oil viscosity, formation of sludge and varnish, corrosion of metallic parts and foaming. Anti-oxidants help inhibit this oxidation process.
  • Anti-wear additives - Anti-wear additives prevent direct metal-to-metal contact between the engine parts as they lay down a protective, sacrificial film. The use of anti-wear additives results in longer engine life as they reduce wear in the engine.
  • Dispersants - Dispersants keep foreign particles present in oil suspended so they don't form deposit build-up in the engine.
  • Detergents - Detergents neutralize the buildup of acids which in turn helps maximize oil drain intervals, while at the same time preventing the accumulation of piston deposits.
  • Pour point depressants - Pour point is the lowest temperature at which the oil may flow. Wax crystals formed in mineral oils at low temperatures reduce the oil's fluidity. Pour point depressants inhibit formation of wax crystals, allowing the oil to flow at low temperatures on engine start-up.
  • Viscosity index improvers - Engine oil viscosity decreases at high temperature (i.e., the oil 'thins out'), which causes a decrease in the ability of the oil to lubricate properly. Viscosity index improvers keep the viscosity at acceptable levels, which provide a stable oil film even at increased temperatures.
  • Anti-foaming agents - Agitation and aeration of engine oil may result in formation of air bubbles or foaming in the oil. This is particularly a concern in off-highway engines that operate on varied and uneven terrain. Foaming enhances oil oxidation and decreases its lubrication effect and can cause oil starvation. Anti-foam agents help prevent this from happening.

A high-quality additive package can help diesel engine oils enhance fuel economy, prevent deposits and maintain proper flow and viscosity in hot and cold temperatures. This is important with the increased use of low viscosity SAE 10W-30, SAE 5W-40, SAE 5W-30, and even SAE 0W-40 oils in extreme cold. Shell Rotella offers a portfolio of full synthetic and synthetic blend low viscosity oils to meet the needs of diesel engines for on- and off-road conditions.

You can visit Rotella.ca to find retailers carrying Shell Rotella engine oils. If you need assistance selecting the best oil to meet specification of your engine, you can call us at 1-800-BEST-OIL.