From Christine & Scott Gable,
Your Guide to Hybrid Cars & Alt Fuels.
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A natural gas or propane powered vehicle, like any other vehicle or piece of equipment, is easier to maintain and repair if you understand how it works and what unusual characteristics it might possess.

Natural gas and propane powered vehicles don’t differ much from their gasoline counterparts (except, of course, much lower emissions). They use basically the same kind of spark ignition engine, and all other parts in the drive train are identical. The one major difference that affects the maintenance of these vehicles (other than the type of fuel burned), is the fuel storage and delivery system. In order to properly maintain your natural gas or propane powered vehicle, it helps to understand this unique system.

The Fuel Tank – The Plumbing

Propane is stored in liquid form, and natural gas can be stored either as a liquid or as a gas. But to maintain either fuel in its stored state, it must be held under very high pressure—around the 200-plus PSI range. As the engine runs, the liquid in the tank “boils-off’ into a vapor state in the upper regions of the pressure tank and continually replenishes the drawn-off vapor that is burned in the engine.

To accommodate these high pressure requirements, natural gas and propane vehicles are equipped with specially constructed high pressure storage tanks to contain the fuel, along with pressure regulators that step-down the final delivery pressure for the fuel metering system. All of these components are built to exacting standards and are able to withstand any ordinary exposure that the vehicle may encounter.

Maintenance Tip: Periodic regular inspection of the tank and its attendant plumbing and pressure regulators should be part of the regular maintenance process. Check the operator’s manual: The inspection schedule is mandated by the manufacturer and should be outlined there.

Clean Burning – Clean Engine – Long Life

The accumulation of unburned fuel, soot and acids are the major contributors to the breakdown of motor oil. It’s not so much that the oil itself “wears out,” rather it’s the depletion of additive packages from the cumulative effects of time and mileage that renders the oil ineffective. When motor oil is kept relatively clean, the anti-oxidants, anti-scuff compounds, viscosity index improvers (and myriad other additives) don’t take such a “lickin,” so they can keep on “tickin.”

One of the biggest benefits of natural gas and propane as automotive fuels is their clean burning characteristics. Both fuels burn so cleanly that not only do they produce scant tailpipe emissions, but they also release virtually no by-products of combustion (carbon particulates and acids) into the motor oil.

Maintenance Tip: Because the oil stays cleaner longer, it’s reasonable to expect longer intervals between oil changes—furthermore, the engines themselves often have a longer service life and reduced maintenance costs. And that means regular service parts that last longer.

To keep your natural gas or propane vehicle running its best overall, check out our general maintenance schedule. You may also want to consider keeping a file for all of your service receipts and a small notebook in your glove compartment. It really only takes a minute or two to record the date, mileage and service performed. And the less guessing on your car’s milestones, the more it will reward you with reliable service.

For routine maintenance on your natural gas or propane vehicle, see our General Routine Maintenance for Alternative Fuel Vehicles.

Check out some other great Alternative Fuel Vehicle Maintenance articles.

The Alternative Fuel Bible: Find Answers to Your Fuel & Vehicle Questions