Motor oils used in gas-powered engines

27 November 2015

Question: Can the car tuned to run on compressed methane gas (CNG) be switched to liquid methane (LNG) or propane-butane (LPG) and vice versa?

MITASU OIL expert help: No. The main difficulty when switching from one gas to another is that different types of gaseous fuel stored in vehicle require different reservoirs. Creating "universal" gas equipment capable of working with different types of gaseous fuel is possible in principle, however, such equipment will be more complicated and much more expensive than the mono-fuel one. At this stage, the idea of developing gas equipment capable of working, for example, on compressed methane and propane-butane mixture, would be economically unfeasible.

Question: How does the engine operation change when converted from gasoline to gas?

MITASU OIL expert help: If gas equipment is configured properly and the engine is in technically sound condition, there will be minimal changes in the way it runs. Usually, the consumption of fuel gas equals 100 - 110% of that of gasoline or diesel fuel. In partial load or idling operation, the consumption of gas is higher compared to traditional fuel. At maximum engine power, gas consumption may even be a few percent lower. The dynamics of a vehicle powered by gas, most often, is somewhat worse compared to a vehicle running on traditional fuel.

Question: What settings should be changed when converting engine to gas?

MITASU OIL expert help: Owners of cars with a fitted modern gas system do not need to do anything. Another question to ask is whether the gas equipment is installed and configured correctly. There is a perception that the most popular nowadays "fourth generation" propane-butane gas equipment is able to determine and adjust the ignition timing when switched to gas. This is not so. The gas controller determines the gas injector opening times (i.e. the amount of gas supplied) depending on engine speed, ambient temperature, gas temperature etc. It is very important for the gas engine that the ignition timing is adjusted correctly. It should be taken into account that the octane number of gas fuel is significantly higher than that of gasoline. Propane-butane mixture has an octane number between 102 - 106 units, and methane - up to 120 units. Thus, the ignition tuned to gasoline’s octane number would be "too slow". Therefore, when switching to gas, there may be loss of dynamics and increased fuel consumption and, under certain conditions, the exhaust valves may "burnout". Also, another feature of engines running on gas is that they require a cleaner air filter, and therefore the replacement interval should be reduced.

Question: What are the requirements to motor oils used in gas-powered engines?

MITASU OIL expert help: In comparison with traditional motor fuel, the combustion of gaseous fuel produces more water and nitrogen oxides. Hence, the oil for gas-powered engines must be resistant to the effects of excessive moisture and nitrogen oxides (nitration). Furthermore, engine oils for gas engines must contain a limited amount of organometallic additives and have lower sulfate ash content compared with conventional oils. This is required in order to protect valves, piston heads, injection nozzles and combustion chambers from high temperature deposits, which adversely affect the running of the engine.

Question: Should oil meet different requirements when used in engines running on different types of gas?

MITASU OIL expert help: If we are talking about car engines designed to run on conventional fuel and subsequently converted to gas, it is sufficient to have motor oil that meets the above requirements, regardless of the type of fuel used - methane or propane-butane. If we are talking about industrial engines originally designed to work on a particular type of gas, then both the engine design and the requirements to motor oil may differ significantly.

Question: How does Mitasu solve the issue of adapting their oils to gas-powered engines?

MITASU OIL expert help: We have both universal oils of "Platinum" series with high oxidative stability and low sulfate ash content, which allows them to be used in gas-powered car engines, and oils enhance with special additive packages improving resistance to negative factors arising from gas-powered engine operation, for example, MJ- 124. MITASU MOTOR OIL SL 10W- 40 Synthetic Blended and MJ- F11. MITASU SPECIAL F 5W-30 100% Synthetic.