So I was changing my oil the other day and I noticed my coolant reservoir was low. No worries, I thought, I haven't ever filled it up before. I topped it off to the max line and now today it's back to halfway empty. It's not just leaking because there are no spots on my driveway from it. I thought it might be my water pump because it had antifreeze around the seal when I changed my oil but I cleaned it then and it's still clean today. Where else could it be leaking/burning off? Any help at all would be appreciated. Oh, and it's a '98 KA 4-banger