While I am posting stuff the Oronite site, how about this:
"New and upcoming engine oil specifications include LSPI prevention. ILSAC GF-6 is expected to include a Ford engine test to discriminate oils based on LSPI event prevention (reduction). Thus, all oils that make GF-6 claims will need to be formulated to address LSPI. Additionally, many OEMs are developing in-house LSPI tests for their own engine designs. For example, GM's dexos1™ specification now includes a GM stochastic pre-ignition test. This test is similar to the Ford test used in GF-6, albeit at different operating conditions.
When comparing the many and varied tests for LSPI impact, it is important to understand the characterization and quantification of an LSPI event can have a bigger impact than different OEM hardware. It is known that LSPI can lead to high pressures, thus one obvious way to quantify LSPI is to monitor the in-cylinder pressure for abnormal spikes. Another approach is to simply monitor for any cycle where combustion starts before the spark, as that is undoubtedly pre-ignition. While these differences in details may seem trivial, they can significantly impact the interpretation of the test results, and in turn, formulations.
It is important to ensure that any new engine oil specifications be based on performance (such as in the newly available engine tests) rather than on chemical limits. Although lowering calcium was one of the initial levers identified for reducing LSPI, it is not the only lever, and calcium detergents have benefits in other performance areas. Oronite has established a firm understanding of formulating for future specifications with LSPI requirements, while still being committed to delivering performance in piston deposit control and neutralizing acids from combustion processes."