Different engines exhibit different degrees of sensitivity to oil
overfill. My one data point regarding the 4.3 as installed in the
S10-based Blazer is that it's not too crabby about it. At the other
extreme would be the 4AFE in my mother's Corolla, which emits a faint
but distinct "hey, lemme outta here!" noise at idle (goes away with any
noticeable revs) if you put in a bit too much oil.
Note that if you replace oil by lining up the empties rather than by
dipstick measurement, there *is* going to be some error unless you
carefully let all the oil drain down through the engine and then into
the drip pan.
Being in a hurry or doing it on a surface that slopes in the wrong
direction -- common sins of Lube'n'Leave and of do-it-yourselfers,
respectively -- are pretty much guaranteed to leave some ounces of old
oil in there. This is worsened, of course, by car-manufacturer brain
trusts who choose not to design oil pans such that a change with new
filter consumes an integral number of quart bottles, as it usually did
in days of old.
Anyway, I'm with the fellow who advised loosening the plug enough to
let several ounces trickle out and then tightening it back, adding more
to achieve a level no higher than the hashmarked "normal" range of the