Originally Posted By: CT8
Now to ponder at what concentration does the Calcium start to promote detonation? And is this with manual trannies or automatics ?
This is from an article in Fuels And Lubes International 2013...
"Calcium showed the most dominating effects on LSPI frequency as increased calcium detergent raised LSPI frequency, Hirano said. In fact, the impact was so strong that raising the percentage of Ca from 0.1 to 0.2% increased LSPI frequency by a factor of three. However, further increase to 0.3% had an insignificant effect on LSPI frequency.
Molybdenum and phosphorus on the other hand, showed good suppression abilities as the LSPI frequency decreased when these elements were increased. At values of 0.07% and 0.15% by mass of MoDTC and ZnDTP respectively, LSPI disappeared. The contribution of Phenolic AO was not found to have any significant effect on LSPI frequency in any manner.
The tests also confirmed the substantial decrease in LSPI frequency without the detergent. Experiments were conducted on GF-5 oils and two samples were compared, with and without detergent, which showed that in the case of the sample without detergent, the LSPI frequency was substantially lower than the oil sample with detergent."
http://fuelsandlubes.com/digital/fli/2013-Q3/files/assets/basic-html/page43.html
Taking the PPM levels from the PQIA's testing of 5W30 synths in 2013 and translating them into a percentage, Mobil 1 was about 0.12% and the Pennzoil Ultra at that time (the one with the 6.6% NOACK that was discontinued) was about 0.26%. Most of the oils they tested were just over 0.2% except for M1 and Castrol Edge (0.076%), but I'm pretty sure the latter was reformulated with more calcium.
I'm honestly not sure if this matches the levels referred to in the paper, though...it seems like the paper is using percentage by mass, but I don't know if that means the calcium alone or the calcium carbonate detergent. I'm also not sure if the PQIA numbers are by mass and if they refer to the calcium or the compound of which it is a part.