Basestock does have considerable impact in the cleaning ability of an oil.
Esters have higher solvency that most other basestocks and higher polarity as well, so they can offer better cleaning ability. In contrast, Grp IVs have low solvency and polarity so require additives to mitigate these things. Esters are also kind to seals while Grp IVs require additives for this.
There are even cleaning and seal conditioning products that consist of nothing more than esters. ARX comes to mind.
In the bad old days before we had all of these fancy additive packages, it was the solvency and polarity of the basestock that allowed the oil to work well enough on short drain intervals.
Esters have higher solvency that most other basestocks and higher polarity as well, so they can offer better cleaning ability. In contrast, Grp IVs have low solvency and polarity so require additives to mitigate these things. Esters are also kind to seals while Grp IVs require additives for this.
There are even cleaning and seal conditioning products that consist of nothing more than esters. ARX comes to mind.
In the bad old days before we had all of these fancy additive packages, it was the solvency and polarity of the basestock that allowed the oil to work well enough on short drain intervals.