Harley Davidson WL oil change or refil?

[epazikas]

Dear colleagues, when it comes to oil change x oil refil, what should be the best approach to do? Or both?
I have a Harley Davidson WL and normally the oil is refilled when it gets necessary (ie whenever the refill mark is reached), however should be the oils be totally drained and replaced as well even thou if the motorcycle is seldom used?

Another question I have is regarding additives to the oil. Should it be used or is it recommended to use a portion of Marvel Mystery Oil blended with the SAE 50 oil? I like the mineral Castrol that is still produced for antique vehicles.

Thank you!

[Architect]

I change mine every Spring, not a lot of money or time. You will be surprised how sludgey the oil gets at the bottom. Yes that is a word from a technical bulletin. Good luck.

[epazikas]

Dear colleagues, when it comes to oil change x oil refil, what should be the best approach to do? Or both?
I have a Harley Davidson WL and normally the oil is refilled when it gets necessary (ie whenever the refill mark is reached), however should be the oils be totally drained and replaced as well even thou if the motorcycle is seldom used?

Another question I have is regarding additives to the oil. Should it be used or is it recommended to use a portion of Marvel Mystery Oil blended with the SAE 50 oil? I like the mineral Castrol that is still produced for antique vehicles.

Thank you!

thank you!