Was told that it is best to have the level half way between full and add.

Is there a reason for this?

Have a 2008 Heritage

Thanks,

 

Yes, there is a reason for it.

Many people, not everyone, who fill the oil bag to the full line will experience oil blow by. This is when oil is forced out the crankcase breathers and into the air filter. The air filter will get saturated with oil and either drip the oil or the oil will mist out the filter and onto the bike or rider. To keep this from happening, it is best to fill the oil tank to a mark halfway between add and full.

 

With bike straight up, the oil level should be about 1 to 1-1/2 inches below the bottom of the filler neck. Just eyeball it.