blue smoke on cold start up

2005 CHEVROLET SILVERADO
111,000 MILES
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DECKER24
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z71 4x4 5.3 v8 ex cab. when I start it up in the mornings I get a small amount of blue smoke coming out of the exhaust. it only last for a few seconds and goes away . I use mobile 1 synthetic 5/30 oil. change oil every 5000 miles. could this be a valve seal, pcv valve or what ? thanks ken
Oct 23, 2013 at 2:17 PM
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CARADIODOC
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Hardened valve guide seals are the logical suspect if the smoking stops very quickly. Oil runs down the valve stems into the combustion chambers when you stop the engine. That can be aggravated by excessive gas in the oil from a previous running problem. That will clear up once all the gas has vaporized and been drawn out.

Your engine really isn't old enough or has enough miles for this to occur yet but that is the only thing that will cause smoke only at start-up.
Oct 24, 2013 at 5:40 AM