"A connecting rod that breaks at high speed is like a shrapnel grenade
detonating inside the motor. In Fieros, chunks of broken metal flew with
such force that they ripped through the engine block. Oil would spill
onto the hot exhaust pipes, and often ignite. The Iron Duke engines used
in early Fieros also suffered from a defect in the way their blocks were
cast that, in some cases, caused the engines to leak oil or lose coolant.
Since the Iron Dukes in Fieros ran a quart low to begin with because of
the customized oil pan, losing more oil quickly created big trouble."

soo... instead of having big trouble by running a bit low on oil... is putting in too much better?

No, too much will cause it to foam and result in loss of pressure to vital spots. also could build more internal pressure blowing out front, rear, pan seals. also could cause some blowby. Low is Better than too much.

Oil capacity list (I'll add this to the 4 cyl QRG one of these days...)

Original 84 3.5Q 5W-30 PF47 filter
post recall 84 4Q 5W-30 PF52 filter

All others 4Q 5W-30 PF47 filter
PF52(fram xxx3980) will fit and increase capacity slightly.

If you are very slightly over, It should not cause a problem. By slightly I mean 1/4 quart. More and you risk foaming the oil, which causes another set of problems...

Generally, You should not fill a Fiero above the full marks with One exception.

IF you have an 84 THAT HAS NOT had the recall done.

In this case ONLY:

drain the oil and remove the filter.

install AC PF52(Fram xxx3980)

Fill with 4 quarts of oil.

run motor to fill filter.

stop motor, and allow it to drain back at least a few minutes.

Check the level. This level is your full mark.

Fram # is listed because the fram number system is used by several brands of filters.

Good advice to use a PF52 oil filter rather than the shorter PF47. The reason for the oil foaming is due to high level, because the crankshaft would be turning in the oil in the pan-not good. I would change my oil and fill it with 4L. It always ran 1/2L over full.