Lubricating Natural Gas Engines
Lubricating Natural Gas Engines
Years ago Natural Gas Engines were usually only found in corn fields for irrigation or as a pump drive at a natural gas well. Today they are everywhere and growing in number. These units are being used for transportation, power generation, pumping stations, and agriculture. Many major cities have converted city vehicles, buses, and public transportation to CNG, LPG, or LNG. Companies like UPS and FedEx are switching many of their short haul trucks to natural gas, a large number of landfills have installed gen-sets, and the list goes on and on.
Typical gases include natural gas, sour gas, city gas, sewage gas, landfill gas, CNG (Compressed Natural Gas), LPG (Liquid Petroleum Gas) and LNG (Liquid Natural Gas). Each of these sources need to be handled and treated differently, to deal with contaminates and environments.
Certain gas sources may require pre-treatment prior to use in an engine. One example is land-fill gas, it must be chilled and filtered prior to use to remove contaminates and harmful components.
Cylinder due to silicon from an unfiltered landfill gas
Stationary and Mobile Engines
Natural Gas Engines are divided into two main groups: Stationary and Mobile. Lubricating Natural Gas Engines require a different approach for both types.
- The Mobile units include buses, trucks, automobiles, and some equipment. Many of these units are modified diesel engines and the gas is mixed with the air prior to entering the combustion chamber. SWEPCO 308 is recommended for these engines. The ash level is in the “medium” range and suitable for use in mobile natural gas engines. (see chart 1) These engines mainly rely on CNG or LNG as a fuel supply.
- Stationary engines are mostly used for power generation and pumping stations. These engines may use any of the gases from pure natural gas to landfill gas. SWEPCO 304 (product info on request, product information will to be published soon) is recommended for these engines and contains a “low” ash level.
Chart 1
| Ash Content ( % wt) | Classification |
| <0.1 | Ashless |
| 0.4 to 0.6 | Low Ash ( Universal) |
| 0.7 to 1.0 | Medium Ash |
| >1.0 | High Ash |
Ashless lubricants
Ashless lubricants are generally used in two-cycle engines to help reduce port plugging and in four cycle natural gas engines. The ash content must be sufficient to prevent valve recession, but not so high as to cause ring sticking, plug fouling, or catalyst masking.
Currently there is not a standard classification system for gas engine oils and they are generally approved via field trials.
SWEPCO 304 Heavy Duty Low-Ash Gas Engine Oil can be used in most of these engines including: Superior, Caterpillar, Waukesha, Jenbacher, Dresser-Rand, and Man. Cummins has several different engines with different requirements so check with us first.
SWEPCO 304 is now available in a 15W40 for wider operating range and better performance.
Please contact your us if you have any questions about lubricating Natural Gas Engines.
Source: SWEPCO
