Ford Mustang: Oil and Electrical Gauge Questions

Oil:

Hello fellow newsgroupers! I have a 91 5.0 LX with approximately 102,000
miles on the motor. Two weeks ago I changed the oil (Valvoline Max Live
10w40) and filter. I went approximately 1500 miles past my normal 3000 mile
change.

I have a few questions...

1. Does the gauge display oil pressure?

The gauge from mustangs of that year, is a vertical indication which reads
"N-O-R-M-A-L" with the N at the top of the normal range and the L at the
bottom. My gauge at idle hover right at or below the "L", but rises to
about the "A" during normal driving.

2. Is this normal, should I be concerned? I checked the oil level, and
that is good. If not, what corrective actions should I take?

Electrical:

At idle, or a stop light, (during the day with the air conditioner running),
the charging indicator will dip down close to the - (negative) symbol on the
gauge. At night with the air conditioner and lights on (once again at idle
or a stop light) I get the same indication. However the needle will move
upwards to the + (positive) symbol during normal driving.

Same question as above. Is this normal, should I be concerned? If not,
what corrective actions should I take? Any advice is appreciated.

Thomas
1991 5.0 LX, AOD
Completely stock with the exception of a
Densecharger Cold Air Induction Kit

"sariwa1" <net> wrote in message
news:n30_a.10120$.. 

I'd be willing to bet that this is electrical too. As Serge pointed out,
this is typically an issue with the sender or the gauge, not oil pressure.
I've had these cars reading almost 0 oil pressure. You'd think 5,000 miles
of 0 oil pressure would cause the thing to at least make some noise, if not
lock up.

I'd do as Serge suggested and test it with a separate gauge that doesn't
rely on the sending unit. If it's good, you might want to try to replace
the sending unit as they're known to go bad, clean up connections that are
known for corroding.
 

Your battery voltage could be quite a few things. Corrosion of any point of
the charging system (including the block ground) will cause an issue. At
this moment in time I'd be happy with the situation you're in because mine
needs a block ground and I can't get the bolt out.

With accessories off and the car running, you should get, as Serge said, 14V
at the battery. The car, with stock pullies, should also be able to handle
the A/C on at a stoplight without getting that close to the red zone on the
gauge. If you're talking it goes below the middle line and to the next one
down, that's ok... if you're approaching red, you have problems somewhere.
You could get the alternator checked (had mine done free at a local shop),
get the charging system checked (free at places like Advance Auto, Auto
Zone, etc), and research any grounding issues.

Good luck...

JS