There are a lot of misconceptions when it comes to natural gas engines, but in reality, natural gas powered trucks can deliver plenty of benefits. Ultra low NOx engines fueled by natural gas offer a low-cost pathway to zero emissions and lower fuel costs compared to diesel.

With a range capability of more than 500 miles, natural gas engines are well-suited for regional and local routes, because they don’t need to be refueled mid-route. Natural gas is a good option for any fleet running return to base trucks with behind the fence refueling capability.

If you’re not familiar with natural gas engines, you might have questions about their overall reliability since up-time is a critical factor when considering engine options. When properly maintained, natural gas engines can deliver excellent reliability and reduce unplanned downtime.

At Cummins Westport, we’re focused on helping anyone considering a natural gas engine make an informed purchase decision, and to help current NG engine users better understand maintenance intervals so they can get optimal performance out of the engine.

Caption: Offering 320 hp / 1,000 lb-ft torque, with improved performance and reliability, the near-zero emissions L9N is a great fit for transit, refuse, and truck applications.

Maintenance Best Practices – Be On Time

In the past, published maintenance guidelines have been based on mileage, hours, or some other specific time frame for when the specific maintenance item was due. This led to confusion and missed intervals.

Today we recommend calculating maintenance intervals based on your fleet’s average speed and the total number of hours the engine runs. This is best obtained by using data from Cummins InsiteTM 

  • Your average speed includes all idle time
  • (500hr interval) x (Avg MPH) = miles driven in 500 hrs.

Pay Attention to Oil Drain Intervals 

One of the most critical steps you can take to keep your natural gas engine running smoothly is to stay on top of your oil changes. Natural gas engines do not tolerate missed oil drain intervals. When the oil breaks down it can lead to rear main seal failures and piston coking, and piston failures.

Use the Manufacturer’s Recommended Engine Oil

Using the right engine oil will also help deliver optimal performance. Cummins Westport recommends using CES 20092. It delivers longer oil drain intervals and contains the best additive package for use with natural gas.


Change Spark Plugs

Because natural gas engines have significantly higher cylinder pressure and temperatures than passenger car engines, the electrodes of the spark plugs are subjected to greater wear and tear. It’s important to change spark plugs before you have misfire codes using new, pre-gapped plugs. This prevents unburned fuel from reaching the catalyst and prevents “check engine” lights on the dash.

We recommend visually inspecting spark plugs prior to installation to ensure the gaps are in spec* and the porcelain is clean. DO NOT re-gap old plugs.

Inspect Ignition Coils

An 18” pry bar and/or special pliers can be used to help remove coil assemblies that are difficult to remove or that have become broken during removal. Extreme cases may require removal of valve cover and spark plug adapter tube.

Use a cotton swab and isopropyl alcohol to remove any excess dielectric grease from the spark plug end of the coil extension spring. Do not apply dielectric grease to new spark plug boots. The boots are pre-greased.

For locations where salt is used on roads in winter should use anti-seize on ignition coil cap screws in valve cover.

In conclusion, by following the recommended maintenance guidelines, a Cummins Westport natural gas engine will deliver efficiency and reliability for years to come.

If you want to know more about getting started with natural gas engines, check out our Natural Gas playbook.

 *Gap specs for reference and diagnostics only Min. 0.013” Max. 0.015”