If it's worn then it's worn. Kero won't help.
I always used Kero to clean my O-ring. I think it is perfect to clean and harmless on the rings. Many people recommend it.
My experience was that a standard chain will stretch quickly and you will have a chance to replace it soon. To me the o was worth it. Maybe it takes a negligible bit more power to drive, but once warm the links pivot easily. Maybe the O weighs a little more.
To me the O was worth it just because it lasted so long and needed so few adjustments. I never noticed any loss of power on my 250.
Chief
I always used Kero to clean my O-ring. I think it is perfect to clean and harmless on the rings. Many people recommend it.
My experience was that a standard chain will stretch quickly and you will have a chance to replace it soon. To me the o was worth it. Maybe it takes a negligible bit more power to drive, but once warm the links pivot easily. Maybe the O weighs a little more.
To me the O was worth it just because it lasted so long and needed so few adjustments. I never noticed any loss of power on my 250.
Chief