98 Stratus Oil smells like gas and is thin

My stratus 2.4 DOHC seems to have some gas getting into the oil a bit. It is not overfull but I just changed the oil about 300 miles ago and it smells like gas now and seems really thin. Also, the car is only getting 22 mpg on the hwy. Is that normal? I have always owned GM cars and I just sold my Malibu with a V6 and it was getting 26mpg. Now this little 4 cyl is only getting 22??? Seems weird to me. No lights on or codes stored. Any advice would be great!
Rob

I would check for a leaking fuel injector. Look at the plugs if one has a lot of carbon on it this is your cylinder with leak.
If you are losing anti freeze look at your water pump or a blown head gasket.
Anti freeze is more white smoke gas more grey to black.

I did just put new plugs in it and didn't notice the old ones looking different. It had those junky bosch platium things in it. I have always had problems with those plugs so I put some autolite plugs in it. It does have a little twinge when it idles. It is not just perfectly smooth. If I have a leaky injector doesn't that usually make it hard to start?
Rob

A badly leaking injector will make it hard to start. Check the fuel pressure with a gage. Cracked exhaust manifolds will fake out an oxygen sensor. This will cause a very rich condition. Start with a flash light and look for any gas leaks around the intake manifold. Start eliminating areas it could get in the engine.
A leaking pressure regulator will allow vacuum to pull gas into the engine.

You may have just answered my question. The car sounds like it has an exhaust leak around the engine but only when the car is cold. Once it warms up the sounds goes away. I tried to look and see if I could see any cracks in the exhaust manafold but I don't see any. It is hard to see up in there though too. It is very cold here in Missouri right now too. Wonder if that is making it get bad mileage and gasy oil.

A crack by the oxygen sensor will cut gas mileage around 40% if close to the sensor. Look good when it warms up.

Are you saying to look for the crack when it is warm or cold? Is the Oxygen sensor back there screwed right into the manifold? I don't remember seeing it but wasn't looking for it either.

I'm retired now some are on the intake manifold others are in the exhaust system. Normally a crack is visible hot or cold. I've had to retap some inlets for oxygen sensors. These were loose and you could wiggle by hand.
Just use a good flashlight and look. Also look for any item on the fuel line that has a vacuum line hooked to it. Trace both inlet and outlet fuel lines back towards the frame from the engine. The amount you are talking about I think vacuum is pulling in fuel somewhere.

Well I keep checking the oil and it is not overfull and last night I really looked closer and it does seem a bit thin to me and smells a bit gasy but not as bad as I first thought. It is only getting 21.7mpg on the hwy. I would think a little 4 bangger would do better than that. I will try to jack it up and get a good look at that manifold and Ox sensor hole etc.

The 2.4 has two oxygen sensors, an upstream and a downstream. They are located, like their names suggest, upstream of the catalytic converter, and downstream of the cat.