Lead Replacement Petrol (LRP) Technical Bulletin

1. What is Lead Replacement Petrol (LRP)? LRP is simply Premium Unleaded Petrol (PULP) to which the refineries include an additive to provide Valve Seat Recession (VSR) protection.
2. Why do we need LRP? Lead (or more accurately, tetraethyl lead) performed two functions in petrol: Firstly, it boosted the octane level of the petrol. This meant that the refineries could reduce the cost by producing relatively low octane petrol and by simply adding lead the octane was increased to a satisfactory level. Secondly, as the fuel was burned, lead oxide was deposited on the valve seats, which provided a cushion to protect the valve seats. Many pre-1986 engines were high compression and had cast iron cylinder heads. The valve seats were simply cut into the soft cast iron. Without the protection provided by the lead oxide deposits on the valve seats, the valves (through continually pounding shut) would eventually recede into the soft cast iron seat. The result was that soon the valves could not close properly and the exhaust valves would ultimately burn out. All engines produced for the Australian market since 1 January 1986 have been fitted with hardened valve seats to avoid VSR. All of these engines, of course, run exclusively on ULP
3. Which pre-1986 vehicles MUST use LRP? Any engine that has a cast iron cylinder head and is not fitted with hardened valve seats.
Typical vehicles are:
• All 6 and 8 cylinder Holden Commodores, Kingswoods, Statesmans, Premiers, etc.
• All 6 and 8 cylinder Ford Falcons, Fairlanes, Cortinas, F110s, F250s, F350s, etc.
• Virtually all American 6 and 8 cylinder engines
4. Which pre-1986 cars can operate safely on ULP? Many European and Japanese-built engines can run happily on ULP or PULP Primarily these are vehicles with relatively low compression ratios and have aluminium cylinder heads that were originally fitted with hardened valve seats. If you wish to run an engine on ULP or PULP and are unsure of the safety of doing so, always check with the vehicle manufacturer, otherwise severe damage could occur.
5. What is the Octane Rating of LRP? The octane rating of LRP is 96 RON, which is the same as leaded petrol has been in recent years.

source: http://www.nulon.com.au/facts/Factsheet%2520122.pdf