started up the truck this afternoon for the first time today and i noticed blue smoke (oil) coming out of the exhaust, not a lot, and it did go away after a minute or so. The idle was rough and after tappin the throttle to maybe blow out whatever crud was in there...when the revs came down it dropped below 500rpm then just conked out. started it back up and no blue smoke and the idle became normal again. It was about 40 something out today so i wouldn't blame it on a cold weather start. any ideas?

by the way its the 5.7... with bout 64K on it

 

sounds like valve guide seals. When you have any vehicle sitting for any length of time and the valve seals are leaking, they let oil past and it leaks into the cylinder. It could be a very small amount of oil to make the smoke. Less than one capful of a normal size qt container. When you started it up the second time it didn't allow enough time for oil to seap past the seal to even be noticeable enough. Also, when your engine becomes warm the seals expand and then contract when cold. Seals are an easy enough fix from a mechanics stand point if that's indded what the problem is.

 

by a can of sea foam its the best dump one in the oil fill and one in a full tank of gas. works on all trucks/cars

 

yea its nothing i've noticed before but it could be a leaky seal. I've heard of seafoam doing good work maybe i'll give it a try

 

Dirtydog is exactly right. Although I had a similar problem. Same blue white smoke low idle then dies out. Truck sat for maybe 4 hours when I tried to start it. So that rules out sitting for too long. I figured I might have had a little water in the gas tank. It did that once and that was it.