When I first run the engine (as opposed to when it has been running for a bit), I hear a squeeling-like noise that sounds almost like a car sounds when a belt is loose. I was first thinking it might be low hydrolic fluid (but when I raise and lower the drive, it doesn't trigger the sound), low power steering fluid (but steering doesn't trigger it either). It is just when the engine is relatively cold. (This is a 2003 Mercury 4 cyl and is my 1st year with it). The drive lube looks like it might be a little on the low side, but don't know if that would do it. Anyone have any suggestions?

Thanks!

Have you checked the belts?

Agreed, alternator belt slipping because of the load put on the alternator due to recharging the battery from starting.

My suggestion is to consider it a squeaky belt.

You should figure out if it is the belt being loose, or a component being stiff (bearings, etc.)

Would that be due to the battery being too low, possibly because it is getting drained somehow (maybe having something to do with, say for example, a new stereo that was just put in before I purchased it)?

Thanks!

Spray some belt dressing on it. If the sound goes away for a bit then you have a belt problem. Alternator could be one thing. Some idiot using motor oil for power steering fluid could be another.

Should I just try tightening the belts?

Your manual should describe how tight the belt shoul be and where to check the deflection. If it is adjusted properly and there is no grease on the belt and pulleys, it should not squeel.

Usually you check the deflection in the middle of the longest section of belt and it should move about 1/2 inch. Don't overtighten it or it will fry the alternater bearings or water pump bearings, etc.

If it is adjusted properly and still squeels then you may have a bad alternater bearing or other bearing such as power steering or water pump.

And if you have power steering be sure there is enough fluid in it.

Perfect advise

Yes, very valid advice.