This is mainly due to the absense of corrosive acids and carbon deposits, both of which are normally produced by Petrol combustion.

Problems caused inside the engine when using Petrol

Carbon Deposits

When using Petrol, carbon deposits itself in many places within the engine. The types of deposit range from soft sooty coatings in the upper cylinder area to the tough scale formed on combustion chamber walls, valve faces and stems, the crowns of pistons. If the deposits are heavy enough, cubic capacity of the cylinder(s) can be reduced. Friction may retard the progress of inducted fuel / air mixture as surfaces are roughened by deposits. Overheating may be caused due to gradual blocking of exhaust ports by larger deposits. All of these factors combine to significantly reduce engine efficiency and power output.

Also note that the third function of engine oil (lubrication and cylinder head cooling being the first two) is to remove carbon deposits from the upper cylinder area and take them to the filter and sump. As the oil capilliairies, chambers, oil pump and filter are made smaller internally by carbon deposited as sludge (or blocked) the flow of oil is not only restricted but overall oil temperature will increase because less oil is then required to move the same amount of heat. This takes the oil closer to 'Thermal degradation', when the structure of the oil (and its cooling and lubricating properties) begin to break down. Lack of sufficient lubrication, even only for fractions of a second, is the prime cause of engine component wear.

When using LPG instead of Petrol, carbon deposits are reduced to virtually nil. Little or none of the effects described above occur. The result is that engine wear is significantly reduced.

Corrosive acids

These are some of the by-products of Petrol combustion. Not only do they damage the finely machined or polished internal surfaces causing erosion and leakage, but they dissolve themselves into the engine oil as it attempts to remove them. The result can be 'dilution' of the oil, reducing its viscosity ('thickness') and its ability to lubricate the metal surfaces of moving parts. Increases in engine component wear due to the effects of these acids are therefore twofold.

Overall, engine oil does not suffer as much thinning (loss of viscosity) or contamination by carbon sludge when the engine is running on LPG and is much better able to protect the moving parts. Oil change intervals may be extended as a result of these benefits. Certainly the oil will stay in better condition for longer periods.

Don't forget that acids dissolved in the engine oil can attack the components whilst the engine is not running. Any reduction in this is a further benefit.

The rest of the vehicle

Acid attack and carbon deposits also have effects on the exhaust system.

Acids 'eat away' at your exhaust from the inside. The life expectancy of a vehicle's exhaust system has been shown to treble when the vehicle is converted to run on LPG, a direct benefit resulting from the absense of such acids.

Carbon deposits are not built up inside the exhaust system at anywhere near the rate they are when using Petrol. The exhaust system will remain clear internally for much longer. Your engine will run cooler ( hot exhaust gases can escape as quickly as the designer intended them to) and be able to 'breathe' better (there is more space in the inducting cylinders for fresh fuel / air mix to occupy because the 'spent' gas can vacate more quickly).
Both of these benefits help to maintain optimum engine efficiency and power.

LPG is also safer to carry in your vehicle!

To find out why, see our item
'Is my car more dangerous when it has an LPG tank? '