Since its only been since 2019 this change was detected in oil forums, I don't think we have enough of a sample size yet of ESP usage where we have enough anecdotal increases in DI carbon valve buildup due to this variation. It's only a few degrees, but since we are talking about running our engines at the edge of temperature limits this is potentially problematic. Note the ad only mentions 'sludge buildup.įact is in the last few years Mobil 1 has actually reduced their high temperature flash point specification on ESP compared to when it first came out. Part of Mobil 1's marketing strategy is aimed to address this partially but key issue is its marketing and not a honest factual statement that Mobil 1 will prevent DI buildup. Most of these papers are behind paywalls, but while I still had university access to white papers, I did read some of the earlier ones which pointed to SAPS being a significant contributor to emissions clogging and subsequently intake valves may also be at risk from the same processes. The general gist of the studies indicate that lower SAPS and improved high temperature volatility are better for preventing buildup as it is this oil vaporization going into the PCV system along with intake valve blowby which leads to increased buildup. There's been a lot of papers on oil volatility, lower SAPS, DI and carbon buildup.