I never grease either sprocket rails usually blow out before my sprocket.The reason your sprocket tip burned is because you greased it then stopped greasing it. If you never grease it to begin with, it will last a long time with bar oil only as lube. When you grease it it keeps the oil from getting to it, so it relies only on grease. Ours at work never get greased. Never ever. And they are in harsh conditions all the time, and rough operators. I've been there 4 years and never saw a bearing failure.