With my NT-16 I went through like one spur per 1 and 1/2 gallon or less during summer. More when it was really cold (-15 C or colder) but thats my own fault. I think I've only wrecked one second gear though.
I always re allign my spurs before everytime I go out.

WHen you mesh your gears, check your mesh, then give the spur a quater turn and check it again. Check all 4 quadrants of the spur because some of them ar not perfectly round[]

With the OS 18 I was going through quite a few spurs so I just sepnt the money and put in Genesis spurs. No probs since!