"The next test assessed a formulation containing a mixture of 0.159% calcium and 0.042% sodium. Here the mixture almost doubled the LSPI activity when compared to the effect of calcium alone. This implies that sodium is a more aggressive LSPI promoter in the presence of calcium."
"The impact of different types of detergents was also examined. There was no statistical difference between salicylate, phenate and sulphonate or between two different types of alkylate backbones on LSPI behaviour. This confirms calcium as a promoter, regardless of chemistry."
http://www.infineuminsight.com/insight/nov-20…ed-pre-ignition