On petrol versions, a three-way catalytic converter is used as part of the front part of the exhaust pipe, whereas diesel versions have two oxidation catalytic converters in the same position. The catalytic converter is a reliable and maintenance free device and owners should be aware of some factors to ensure its proper functioning throughout its service life. For petrol models it is essential to not use leaded petrol or LRP as the lead will coat the precious metals and reduce their efficiency, destroying the converter in the process. Maintaining the timing and fuel systems as per the manufacturer's schedule is crucial. If there is a misfire of the engine, driving should be minimized until the problem is resolved. Pushing or tow-starting the vehicle is to be avoided to avoid unburnt fuel soaking into the catalytic converter which can cause overheating. The ignition should not be switched off at high engine speeds and fuel or engine oil additives that may damage the converter should be avoided. If the engine is burning oil to the point where blue smoke is evident, then the vehicle should not be used. It is important to remember that the catalytic converter operates at very high temperatures, and therefore after a long run it is important to park the vehicle in a dry spot away from the undergrowth, long grass, and piles of dead leaves. The converter is also delicate and should not be hit with any tool while servicing. A sulphurous smell from the exhaust may occur, which is common and should dissipate after a few thousand miles, changing the brand of petrol may help in the meantime. A well maintained catalytic converter should last anywhere from 50,000 to 100,000 miles and if it no longer works, it needs to be replaced. For diesel models, the same precautions as maintenance and care should be taken.