Engine Synthetic Oil Question

[tr7driver]

I have a 2005 GT vert with 35K miles on the 4.6 V8 engine. I have been using the Motorcraft 5W20 syn blend motor oil for the life of the car. Last November, just before I put the car away for the winter, I changed the oil and used Castrol synthetic instead of the blend.
Yesterday, I took the car out for the first time this season and I noticed that it blew some dark smoke upon cold startup twice. Only at startup. I don’t remember seeing smoke ever from this engine. This has me wondering if there is an issue with the synthetic oil or my engine, or if this is just something from letting the car sit.
Any ideas on this, other things to look for, or other information is appreciated.

 

[Bullitt95]

The dark smoke was probably from letting the car sit for a few months. The best thing you can do is take the car for a long drive on the highway (not driving like Miss Daisy) to blow the "cobwebs" out of the engine.

 

[timjimmy]

What it smoke with more of a blueish tint or black?

 

[Noobz347]

The dark smoke was probably from letting the car sit for a few months. The best thing you can do is take the car for a long drive on the highway (not driving like Miss Daisy) to blow the "cobwebs" out of the engine.

Yep... Some new gas would a step in the right direction as well. Maybe a half a can of seafoam too.

 

[SpartaPerformance]

My Mustang blows bluish black smoke after sitting for the winter but thats only the 1st day.

 

[tr7driver]

Thanks for the replies. I also had Sta-Bol mixed in the tank when I filled it for storage, so I think it is a storage issue. I've driven about 100 miles and added some fresh gas yesterday, and the exhaust has cleared up.

 

[Paul G]

Back in April I started mine up for the first time, a whole bunch of crap blew out the back and then cleared up...
It's normal. Oil sitting at the bottom of the pan for 5/6 mos, the crap gas with ethanol essentially turns to water..

Marine Stabol is the best to use.

 

[Gearbanger 101]

Seafoam is a great fuel stabilizer as well. I wouldn't trust any of them after 5 or 6 months though.