Those two Penrite oils make for an interesting comparison:
Penrite HPR 5 (5W40) a full-SAPS synthetic with API SP, ACEA A3/B4 and MB 229.5 (they showed the MB certificate at one stage).
KV100 = 14.4 cSt,
VI = 167,
Zinc = 1240 ppm,
TBN = 10.4,
SA = 1.28%
Penrite Enviro+ (plus) 5W30 a mid-SAPS synthetic with API SP, ACEA C3 and VW 504 00 / 507 00 (they link to the actual VW license certificate).
KV100 = 11.7 cSt (thick for a 30 grade),
VI = 169,
Zinc = 850 ppm,
TBN = 6.62,
SA = 0.70%
Both are full synthetics, both do their job. The HPR 5 does it the old way with a heavy inorganic (metallic) additive package. The Enviro+ does it the new way with very high quality base stock and I assume some expensive organic antioxidants that don't show up on a regular oil analysis.
The change in direction is motivated primarily from wanting to protect the catalytic converter in the exhaust system and reduce exhaust emissions. It's probably only possible since the dramatic increase in fuel quality via the reduction of sulphur in the fuel.
Most of the world (China, India, Canada, USA, NZ, Europe) is limited to a max of 10 ppm (parts per million) sulphur in their fuel. Australia is the exception, right now our limits are:
- Diesel 10 ppm
- PULP 95 & 98 RON 50 ppm
- ULP 91 RON (~87 Octane) has a 150 ppm sulphur limit.
According to the manufacturer often real world levels at the Aussie pump is typically 15 to 30ppm (petrol). From memory, the old school leaded Super from decades ago was something like a 800 ppm limit. Anyway the talk is Australia will move to 10 ppm limits for all fuel sometime in the near future (late 2024 to 2027 ?). The drive is to reduce emissions like NOx.
From the engine oil point of view, less sulphur in the fuel means that less acid fighting TBN is required and therefore SAPS / SA% level can be reduced while keeping the oil change interval (OCI) to similar distances. Also a lot of the job of the very early ZDDP oil add was to act as an antioxidant to stop oxidative thickening of the oil. Now with less sulphuric acids being formed from the fuel and more stable base stock being used for the oil, then less ZDDP is required.
I like my ZDDP & TBN, but I can see where they are going with this, and the modern levels of ZDDP & TBN make sense to me given the improvements in fuel quality. Especially given I change my oil every 10,000km. However I would be worried about a person in Oz who only runs ULP (to save money) and then pushes the OCI to 20,000 km (to save money). I'm sure these people exist.