What is the significance of "ashless" 2 cycle oil?

I just purchased a bottle of STIHL 2 cycle oil. It doesn't say ashless.
Thanks.

The Stihl is good oil.

"Ashless" is for air-cooled engines AFAIK. The idea is you want to stay away from 2S oil designed for water-cooled for boat engines. Ours get much hotter.

Any oil designed for motorcycle premix or 2S lawn equipment should be fine.

Actually, the ashless oils were designed for water-cooled outboard engines. The low-ash oils were designed for air-cooled engines. The description of ashless and low-ashless simply refers to the results of a combustion test. The detergent in the ashless oils leaves no ash when they cook the oil at high temperature. The low-ash oils have a detergent that leaves a little ash when they cook the oil. The ashless detergent works best in low temperature water cooled boat engines. The low-ash detergent works best in hotter running air-cooled motors. Your best bet for our engines is to run a low-ash oil. Some oils are designated as "all-purpose", but they are a compromise by design. The confusion comes in when some manufacturers of model engines specify an ashless oil (like Lawnboy) for break-in. I would rather use Penzoil two stroke oil for air-cooled engines (low-ash).

Thanks Diablo. I guess I'll ditch the Stihl "all purpose" oil.
I have some lawnboy ashless also. Maybe I'll look around for some "low-ash".