Originally Posted By: Virtus_Probi
Originally Posted By: bigj_16
Originally Posted By: Virtus_Probi
Additive manufacturers have been good about sharing LSPI/oil info and have indicated that sodium is a big LSPI accelerant in the presence of calcium and that ZDDP helps quench it. It might be possible that a good dose of calcium would still be OK for LSPI if there is no sodium present and a bigger dose of ZDDP than SN allows is used, and Amsoil is definitely a company that is OK with putting out non-API oils.
I am definitely very curious about what their new SS 0W30 and 5W30 oils will look like!
Not discounting the sodium, but some of the studies I read mentioned calcium, of any formulation, as the culprit, with no mention of sodium. Can you post a link to the sodium study? I think something that would be prudent, right now, would be to go with a lower calcium pack, i.e. most M1, until this is locked down.
Here's a link for an LSPI study mentioning the impact of sodium...
http://www.infineuminsight.com/insight/nov-2016/quenching-low-speed-pre-ignition
Great post by wemay that brings up the impact of moly, which I had forgotten about! So a high moly oil might be able to handle more calcium and still be LSPI resistant. I really have no idea how stringent the dexos1 Gen 2 LSPI test is, anyway...
EDIT - interesting that the XOM patent gives magnesium half the weight of calcium as an LSPI accelerant while Infineum says it is LSPI-neutral...
Thanx! What I really need to do is shell out the $$ for the SAE paper.
This is what Oronite says about calcium, magnesium, and moly:
"Many factors have been demonstrated to impact LSPI, including: engine designs, fuel composition, and lubricant composition. On the lubricant side, the most noticeable impact has been from the detergent chemistry. Oils with higher concentrations of calcium, which is found in many detergent systems, have been shown to increase the frequency of LSPI. The exact chemistry of the detergent is less important to LSPI than the calcium content. Conversely, magnesium-based detergents do not seem to promote LSPI. Although reducing calcium may seem like a solution to control LSPI, there may be other performance tradeoffs to consider. In addition there are other additives that can also help reduce LSPI events. This provides an opportunity to formulate for robust LSPI performance, while maintaining the level of detergency needed to help keep engines clean and neutralize acids generated during combustion.
Aside from the detergent system, there are many other additive and lubricant compositions that can influence LSPI. Molybdenum compounds, for example, not only provide frictional benefits, but also have been shown to decrease LSPI when used at high levels. Base oils also affect LSPI events. Both the quality of the base stock (i.e. Group II versus Group III) and the viscosity can have secondary effects on LSPI. The effect on LSPI from these other lubricant aspects are not as significant as the detergent system, but can shift the LSPI frequency in oils that are more prone to LSPI."
I know why, in the Infineum cited SAE study, that they used the "clean" gasoline that they did, but I wonder if there is any issue with "street" gasoline adding to, or possibly, increasing the LSPI in combination with the lubricant.