Difference between HDEO and PCEO?

[Hohn]

There's significant differences in the additive package, particularly detergents and dispersants. A diesel produces a lot more soot which demands a different DI pack to manage that soot. The downside is that higher detergent content can work against ZDDP (anti-wear). A gas engine is less concerned about soot and more concerned with higher piston and bearing speed and low speed pre-ignition (LSPI) in GDI engines. An additive package with less detergent (particularly less calcium) is needed to prevent LSPI.

All this. Great post.

Diesel oils today are limited in SAPS (<1% per CJ-4 and later), but what matters is how the blender is spending their SAPS "budget."

Diesel oils are today dominated by soot dispersant considerations because emissions-controlled engines are soot-generating fools. Add to that the pressure for longer and longer service intervals, and you need an oil that spends a significant amount of its additive pack managing soot.

Given the zero-sum nature of add packs, I'd prefer not to spend that on soot dispersant dosing my gas engine doesn't need. I'd rather have more antiwear and oxidation resistance instead.

If you don't have a emission-controlled (EGR) diesel, most A3/B4 oils are likely better "diesel" oils than what is CK-4 or FA-4 today. At least in terms of wear protection.