I know what you are saying
you may have had similar experience to me in that most of the low ash oils are 5w-30 but engines on that consume more oil.
We are VAG specialists and all the engines running the VW longlife (on variable servicing) oil consume quite a lot of it but when you switch the cars back to fixed interval and use the 5w40 VW505.01 C3 oil the oil consumption basically stops.
I think what you gain in having a low ash content oil you lose by sending more burnt oil through the exhaust system.
you may have had similar experience to me in that most of the low ash oils are 5w-30 but engines on that consume more oil.
We are VAG specialists and all the engines running the VW longlife (on variable servicing) oil consume quite a lot of it but when you switch the cars back to fixed interval and use the 5w40 VW505.01 C3 oil the oil consumption basically stops.
I think what you gain in having a low ash content oil you lose by sending more burnt oil through the exhaust system.