Oil change intervals have been well studied on the Savage.
Start with Suzuki Standards as stated in the full service manual, they want you to change the oil every 3,000 to 5,000 miles (they assume a dino oil in this procedure as there weren't many synthetics out there in 1987). For many of us, that translates to changing the oil once a year.
Here at SS.com we have recommended oils up in the Tech Section. We have recommended oils because the normal, off the shelf oils that were available (with enough ZDDP in them) in 1987 haven't been available for like 15 years now.
The current off the shelf car oils are way way less than what our bike requires. An oil that CAN support our antique valve train is really sorta scarce now, and certainly isn't common off the shelf any more.
http://suzukisavage.com/cgi-bin/YaBB.pl?num=1344471565All but the very first one of these recommended oils are full synthetics which could support extended drain intervals if our air filtration system also supported fine air filtration to match that extended drain interval. But we are stuck with a standard air filter system that allows too much silica (fine dust) to get into the oil over the course of more than one year, so no extended drain intervals for us.
Shame that, the synthetic oils could do it but the air filter can't.
So, buy oil off the recommended list and change it at least once a year (or more often if you just feel lead that way). This is where the state of the Savage oil change sits right now.