What does it mean when all the gas isn't combusting in your engine and a more than normal amount comes out of the exhuast? You know, like when your exhaust smells all gassy and you can see the smoke.

 

Running rich?

 

Back fire(ing?) I don't know, just throwing something out there.

 

yea you are thinking of running rich
I think there are a lot of factors to that
but first of all to make sure.
What color is the smoke?

 

its definitely not backfire
burning more gas than it should be (running rich) is a common problem

 

The smoke is a grayish color, kinda like normal smoke.

 

Thats burning oil. Running rich, you're smoke will be very dark gray/black.

 

Well, I just bought the car and when I bought it, it didn't do that. Since I've bought it, I've changed the oil to Royal Purple (and found out I need a new oil pan gasket) and changed the spark plugs to Denso Iridiums. Oh yeah, I actually run premium gas in the car, unlike the previous owners. What could have changed between then and now? How do I fix it or will the ECU adjust and fix it on its own?

 

Depending on how many miles are on it, the royal purple may be too thin and slip through some old gaps that the other kind of oil didnt allow to pass.

Burning oil could also a sign of burnt piston rings too, did you romp on your car when you got it?
The gas and the plugs shouldn't affect it that much.
To fix it your probably going to need a gasket kit for you motor and start going to town replacing those along with possibly your pistons rings, hope this helps some.

 

What he said ^

Whats the mileage on the motor? The royal purple could be your problem. Its a great oil but you cant use full senthetic on a high mileage motor... well, its not recommended anyway.

 

does it do this when its cold outside?

because all cars do this on startup. really common knowledge, but just throwing this idea out there.

 

if it is darker smoke it probably is running rich
i don't know much about how oil would affect if it burns more gas
but on older cars it is better to use a thicker oil than what is suggested for the car because after years of running you want better lubrication

 

There are around 133,000 miles on the car. I used a 10W-30 instead of the 5W-30 because of the winter time...Oh well, we'll see what happens.

 

Whats the mileage on the motor? The royal purple could be your problem. Its a great oil but you cant use full senthetic on a high mileage motor... well, its not recommended anyway.

^^
Wrong, you can but you should not switch over if from normal to full synthetic if its a high mileage motor. You can use full synthetic with no problems if you started when the millage was lower. Even with high you can but you will most likely need new gaskets here and there