You are right. I also think the same.
In USA, there are engine oils which last 01 year or 15-25,000 Kms (whichever comes first), but car engines are also big, may be like 4000-6000 cc, or may be even more, and they may require oil 6-8L (even more), however, this very same analogy cannot work here in Pakistan and in 1000-1500 cc engine, as they usually require 3-4L engine oil.
To me, IMO, Oil sump matters the most! The bigger it is; it may require less change intervals (like 6-8 months or more), however for smaller engines, frequent oil changes may be required.
