My guess is either it has few miles on it or you didn't buy it new.

Late 04 thru mid 05 HD had a batch of defective or sub standard valve stem seals. They fixed most bikes under warranty.

On mine oil consumption became excessive and loud flame throwing decel popping was the norm.

Ran a compression check had 125-130 on front cylinder and 55 on rear cylinder.

 

It has a lot to do with how hot the oil gets. I was going through Nebraska in 2006 on a 95 degree day, brand new black top, and we had been ridding for several hours. All six bikes I was with showed zero oil pressure. That night I checked my oil and I was down about a half a quart. On average I go through a quart every 5K miles and I am at 14K. My brothers 06 goes through a quart every 2K miles. According the local Harley service manager a quart every 1K miles is normal!!!! Seems a little excessive to me.

 

I go thru about a 1/2 quart between changes and change every 3000 miles. I was always told if it's a Harley it leaks oil