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Further, while the backpressure increases as the cake builds up, the ash loading ultimately raises filtration efficiency — and does not affect performance or fuel consumption. These findings tell us that ash cake buildup can help boost GPF performance while keeping emission levels well below the regulation limit. With the highs and lows covered, we turned to lubricant oils that produce mid-level ash buildup.
2. A balanced detergent formulation that met the LSPI compliance threshold (Oil B) When using a total ash load of 42 grams — equivalent to 200,000 km of on-road operation at a normal oil consumption rate — GPFs easily met emissions requirements. Figure 8 illustrates PN and PM trends in both Oil A and Oil B over the entire accelerated aging test. To better understand the early filtration process, we studied PNs and PMs both upstream and downstream of the GPF. Our research showed that as ash loading continued, filtration efficiency improved the ability to lower particulate emissions.
Soot Oxidation Additionally, we explored the impact of these oils on GPF soot oxidation. Using eight oils with varying amounts of ash, we built a system to asses each lubricant’s soot oxidation rate. Figure 9 illustrates the relationship between the detergents used — whether Magnesium (Mg) or Calcium (Ca) based — and the levels of ZDDP and sulfated ash.
Figure 8 — Ash caking in reduced SAP lubricants help keep particulate emissions low.
Reduced Ash Oil Testing and Results
Figure 9 — Building a matrix of eight oils helped us begin to understand their soot-oxidation levels.
Expanding on our testing, we also researched two reduced ash lubricant oils: 1. A modern product meeting ACEA C3 (Oil A)
We assessed the carbon oxidation rate for soot samples generated in an engine using each of the eight oils. The soot samples we tested
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