I have been researching ash content in motor oil and what it means to motorcycle engines and engines in general. There seems to be some conflicting information out there and no real definitive answers.
Many of us use or want to use diesel engine oils in our bikes due to better specifications and price when compared to car and motorcycle specific oils. Diesel oils have many qualities well suited to motorcycle engines. Neither types have catalytic converters or much in the way of emission control except for, perhaps, California bikes.
Ash content is proportional to the detergent levels in oil. Some ash content can be contributed as a by product of the oil base itself but mostly from the detergents present. Ash is said to plug up c. converters in time.
Diesel engines produce much more engine deposits due to the fuel and the sulphur content in the fuel. High detergent levels are necessary. Diesel engines need to run longer between oil changes due to downtime and costs.
Is this ash content harmful for bikes?
One oil expert said that low ash promotes longer valve life with no real data to back up the claim. I have also read that ash cushions the valve seats during combustion promoting longer valve life.
Ash is a by product of combustion and is bound to cause more combustion chamber deposits. This may be a concern for old engines that do have more oil getting into the combustion chamber due to worn rings and/or worn valve seats and guides. I would not think to be a concern for engines in prime condition.
High ash oils can have better TBN numbers. High TBN numbers are indictive of oils that will neutralize acids, water, oxidation processes, and combustion by products better and longer. These high ash oils should be better for 'extended drain'.
The preceding paragraph holds true for Group 1,2,and 3 oils. It does not hold true for Group 4 and 5 oils which are able to achieve high TBN without high ash.
So. What is the answer? Is ash good? Is it bad? What levels of ash would be acceptable and what would be unacceptable?
We could just use the Group 4 and 5 synthetics and not even worry about the ash.
I invite your comments.
Many of us use or want to use diesel engine oils in our bikes due to better specifications and price when compared to car and motorcycle specific oils. Diesel oils have many qualities well suited to motorcycle engines. Neither types have catalytic converters or much in the way of emission control except for, perhaps, California bikes.
Ash content is proportional to the detergent levels in oil. Some ash content can be contributed as a by product of the oil base itself but mostly from the detergents present. Ash is said to plug up c. converters in time.
Diesel engines produce much more engine deposits due to the fuel and the sulphur content in the fuel. High detergent levels are necessary. Diesel engines need to run longer between oil changes due to downtime and costs.
Is this ash content harmful for bikes?
One oil expert said that low ash promotes longer valve life with no real data to back up the claim. I have also read that ash cushions the valve seats during combustion promoting longer valve life.
Ash is a by product of combustion and is bound to cause more combustion chamber deposits. This may be a concern for old engines that do have more oil getting into the combustion chamber due to worn rings and/or worn valve seats and guides. I would not think to be a concern for engines in prime condition.
High ash oils can have better TBN numbers. High TBN numbers are indictive of oils that will neutralize acids, water, oxidation processes, and combustion by products better and longer. These high ash oils should be better for 'extended drain'.
The preceding paragraph holds true for Group 1,2,and 3 oils. It does not hold true for Group 4 and 5 oils which are able to achieve high TBN without high ash.
So. What is the answer? Is ash good? Is it bad? What levels of ash would be acceptable and what would be unacceptable?
We could just use the Group 4 and 5 synthetics and not even worry about the ash.
I invite your comments.