Yeah usually a little over fill is not a problem. And how do you know it is 1qt over? A wild guess is that 1qt over would be about 1 inch over the full mark on the dip stick, but probably is different for different engines. I don't know 5.8 engines so can't say. On my 460 1qt is maybe 1/4 inch, on my 350 chebby it is maybe 1/2.

If it is just 1/2 inch, no sweat. 1 inch maybe a problem if you do a lot of high RPM driving or you do slalom or drag racing, then you would get windage and maybe foaming. After driving around normally, does your dip stick have a lot of bubbles on it? If so then you are too full and draining the filter probably would fix the problem. A few bubbles are OK. Foam several inches up the stick is bad.

Think about it... the crank is swirling around in the pan above the oil. The factory leaves a fair margin of space above the oil to cover for occasions where someone is reving the engine, driving up steep hills etc. The intent is to keep the oil from contacting the crank in most situations. There is a fair margin of error allowed for. So 1/2 inch on the stick is 1/2 inch closer to the crank, but in most cases is still a decent distance away, I assume. Note that I don't have xray vision and have never tried to measure just how far the oil really is from the crank, so what I am saying is an educated guess and experience with other engines, but not your model. Also think about how deep 1qt of oil is in a drain pan. Depending on surface area in the crankcase, 1 qt of oil can spread pretty thin.

I usually overfill a chebby I drive by about 1/2 qt since I am too lazy to just pour in the 4 1/2 qt called for, I just dump in the whole 5qts. 114,000 miles so far and no problems, ditto many other engines I have owned. Not saying it is a good practice, but unless you are doing unusual driving or your engine is really picky, you don't have a problem.

If you are worried, drain the filter.

Good Luck,

Jim Henderson