I thought I'd pass this on. My engine, which is in pretty good condition, had a little valve chatter for a few seconds after startup, till oil got to the valves. I thought I might have too thick an oil or need an additive. I called IPD and they said check your filter before anything else. If it's a cheap filter, without a bypass valve, it will take awhile for oil to get to the top of the engine. He said get a Mann filter and try that. Sure enough, it had a Champion filter from a quick change place. I got 5 qts of Full synthetic oil from Walmart for $18.00 and a Mann filter from Napa for $6.00. Instant fix! My engine is super quiet now.