Help Need Help!

[LeeS]

I have a 2002 Silverado with a 5.3 Engine.

 

I have just changed oil for the first time at 3222 miles. I am using Mobil 1 Full Synthetic 10w-30 oil.

 

If I let the Truck run for about 3-5min or longer and shut the key off and restart it immediately I see bluish and little black smoke come out of the tail pipes. I have a dual exhaust.

 

If you rev the engine a little after it has idled a long time. It will do the same thing. Do you guys think it is burning oil because it does this or do you think it is flood smoke.

 

[/b]I have removed the cats and am using O2 simulators to fool the computer. What do you think?

 

I need to know if any of you have ever seen this. I smells like both maybe oil and gas smoke. I don't know. It sure does worry me though.

[pipermaru9]

Alot of guys on this site have recommended not changing to synthetic until about the 10K mark. I was going to do the swap but after reading that, I opted for regular dino oil. I changed mine at 2940 and haven't had any problems. And more to the point no smoke. Just my $0.02.

[LeeS]

Thanks for you help. I really appreciate it.

[GreenRado]

LeeS, I don't know if there is any relevance here, but there was a TSB out on several model years from '99 on (don't know exact years covered).

 

It involved replacing the PCV w/ a revised version.  Seems the older version allowed a fair amount of smoking (using up to 1 qt or more per 2000 miles - something like that).  

 

I'd check w/ your dealer.  I remember the TSB indicated the new design PCV does not "rattle" when shook (for whatever that's worth).

 

Just a thought - good luck.

[CityTruck]

Speculation here...

 

I think you may have two problems if you're burning oil and you smell gas.

 

The Catalytic converter is supposed to "oxydize" the unburned hydrocarbons so this could lead to the fuel smell (though you wouldn't benefit from them if they were cold).  Also I think the O2 sensors work with the computer to vary fuel mixtures, etc..  based on their readings.  If you've got simulated 02 sensors, they probably give a constant reading rather than the variable reading the "live" sensors would give so the computer may not be providing the most effecient info to the engine.

 

The oil burning issue would be less noticeable with cats also (if they were hot), but is an indicator of another problem.  Search through the threads here about exhaust smoke and you'll find several instances and fixes for many of the causes.