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Originally Posted by Daniel R
Since we are on the fuel debate, is there any benefits to running leaded petrol? My understanding about the shift to unleaded is that lead additives are not compatible with catalytic converters. My car no longer has cats, so does this mean I can use leaded fuel?
In Australia 98 RON unleaded is readily available, and is all I use in the boxster. I'm just wondering if the lead would somehow help the motor apart from increasing octane. Maybe it lubricates better or something??
Your thoughts are much appreciated.
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The lead used in leaded gasolines was a form called tetra-ethyl Lead and was initially only used in Premium or High Octane gas, which commonly became known as Ethyl - some companies even marketed it under this name.
This additive raised the octane rating of the fuel inhibiting detonation and also helped lubricate and seal the valves whose seats were made of soft mild steel for better sealing. This is why valve adjustment on earlier cars was so frequent -= the valve would get pounded further and further into the seat - the lead acted similar to RTV on a gasket.
Because engines today are not designed to use it, and are machined to much closer tolerances using different materials (esp. the valve seats), and usually with a much lower CR, using leaded gas in today's engines would not likely yield the same benefits. Aside from damamging the cats (by coating the ceramic matrix with lead, thus reducing it's useful surface area to react with the exhaust), it would also make your OČ sensor inoperable after only a few miles.
And, all of this is aside from the obvious environmental issues.
Cheers!