Which mineral oils have the lowest ASH content?

[rearviewmirror]

I'm trying to figure out which oils in the weight of 10W-40, 15W-40, and 20W-50 are lowest in ash. I'm only interested in mineral oil, but discussing synthetic is never a bad thing.

 

[MolaKule]

The lowest oils with magnesium, calcium, and zinc listed in the Used Oil Analyses.

 

[bruce381]

I would add oils with less or NO VII.

The VII while not technically not "ash" forming will leave some residue upon burn off.
bruce