A month ago or so ago, the weather here turned bitterly cold and I started hearing a loud squeak when I started up the car. It would go away after the car started down the road. I assumed it had to do with bitter cold.

Now, the squeaking will either go away for a bit when driving, then start up again and stop again. Also, since it's winter, the heat is on full blast and sometimes when the squeaking starts, the heat will lessen in intensity for a few moments or the lights may dim as well if it's night.

What is odd is that the serpentine belt was replaced last spring, and I can't seem to tell where the squeak is coming from. I opened up the hood this evening, and noticed that there seemed to be what appeared to be an oily substance on the black hood covering the engine, but my oil levels were fine.

Any ideas what this could be? Or is this car on its last legs?

 

In addition, I seem to be losing gas mileage. This seems to have started around the same time as the squeaking. I fill up and dont drive too far or too fast but my tank seems to drop very fast. No gas leaks or anything like that. I have snow tires on but I seem to need to fill up far too fast.