high sulfur level indicates low quality basestock?

[08sienna]

PQIA explains that group I base stock contains much higher sulfur level compared to grp II and III

also I realize that Pennzoil conventional has a lot lower sulfur level than Quaker State Conventional, Mobil super has lower sulfur than Mobil special - high sulfur oils are sold a lot cheaper than low sulfur oils? does this indicate Quaker State Conventional, M Special contains grp I base stock?
Is it safe to think high sulfur = lower quality?

Thoughts?

 

[Tros]

Some additives such as ZDDP, or Molybdenum Dithiocarbamate contain sulfur. Are lower sulfur oils better? I'm not so sure. Some very good oils use the said additives.

 

[Shannow]

Depends where the sulfur got there...is it's left over from refining, it's probably not the best, if it's an additive, it's there for a purpose.

However, even in the former, it helps things like diesel injector pumps a tad.