On the Road Advice

How do I know what kind of coolant to use and which type is most important for your engine?

Coolant technology has changed as engine technology and component materials have changed, particularly with the use of more aluminum in engines. However, there is a misconception that all coolants are the same, and interchangeable. There are two distinctly different types of coolant, older conventional fully formulated and the newer extended life coolant with organic acid technology (OAT). They each protect engines from corrosion very differently and when the two are mixed, both are diluted, and their effectiveness can be significantly reduced.

The primary difference between fully formulated coolants and extended life coolants (ELC) is the length of time and miles each will remain effective. ELCs offer significant maintenance cost savings over the life of the coolant. While fully formulated coolants can provide protection for up to 200,000-250,000 miles, extended life coolants are designed to go 600,000 on-highway miles and beyond with proper monitoring.

• Fully Formulated Coolants contain silicate and other inorganic additives, which along with supplemental coolant additives (SCAs) provide engine and cooling system protection. They offer a stabilized, low-silicate formula that helps reduce deposits and the risks of hard water scale. Fully formulated coolants typically contain nitrite and often molybdate to prevent corrosion damage which can result from cavitation pitting in heavy-duty diesel cylinder liners. Fully formulated coolants can provide protection for up to 200,000-250,000 miles or two-three years in heavy-duty applications under normal operating conditions. The user must monitor the condition of the coolant and make regular additions of SCAs to maintain additive levels.

• Extended Life Coolants offer complete cooling system component protection and contain no silicates. They help to reduce water-pump failures, hard-water-scale deposits and silicate gel (the green goo you often see). They utilize organic additive technology and have the addition of nitrite and molybdate that protect cylinder liners from pitting corrosion damage. ELCs help reduce maintenance costs and improve water pump life, as well as eliminate the need for costly supplemental coolant additives. Shell Rotella ELCs are formulated to provide high performance protection for today’s heavy-duty diesel engines. They offer effective heat transfer, freeze and boiling protection, as well as corrosion protection for the cooling system. ELCs are designed to go 600,000 to 1,000,000 on-highway miles and even beyond with proper monitoring.

• Nitrite Free ELCs are formulated to meet more severe operational conditions of modern, hotter-running engines. Nitrite free coolants provide improved protection of aluminum components including modern brazed aluminum heat exchangers and meet many of the latest OEM specifications. The versatile formulation may also be used in fleets that include passenger cars and light-duty trucks. The coolant is proven for extended life operation in medium and heavy-duty diesel, gasoline, LNG and natural gas vehicles and engines. (ELC NF) offers outstanding heat transfer that is superior to conventional coolants. The coolant has an extended life capability – up to 1,200,000 on-highway miles or 24,000 hours in Class 8 trucks and up to 600,000 miles or 12,000 hours in other commercial applications.

Always be sure to check your owner’s manual or with a qualified service provider to ensure that you use the proper coolant type.

Can I mix Shell Rotella T6 and T5 oils?

You can mix our Shell Rotella T6 with a Shell Rotella T5 diesel engine oil. Just make sure you use the same viscosity grades. Mixing oils with different viscosities is not recommended as it can affect the oil's performance and the engine's health. If you must mix viscosity grades in an emergency, it is recommended that you have an oil change as soon as possible. Always follow the OEM’s guidelines found in your vehicle’s owner’s manual for oil selection.

Lower viscosity oils, like Shell Rotella T6 5W-40 and T5 10W-30, flow more easily and provide better protection at colder temperatures. These oils also improve fuel economy and reduce CO2 emissions. However, it's crucial to follow your Original Equipment Manufacturer (OEM) recommendations when selecting oil, as not all engines are compatible with low-viscosity oils.

For more helpful tips check out our info hub: https://rotella.shell.com/en_us/info-hub/what-you-need-to-know-about-low-oil-viscosity.html