GMC 1998 Savana Van Owner's Manual page 132

Have you recently changed brands of fuel?
If so, be sure to fuel your vehicle with quality fuel (see
"Fuel" in the Index). Poor fuel quality will cause your
engine not to run as efficiently as designed. You may
notice this as stalling after start-up, stalling when you
put the vehicle into gear, misfiring, hesitation on
acceleration or stumbling on acceleration. (These
conditions
may
go away once the engine is warmed up.)
This will be detected by the system and cause the light
to turn on.
If you experience one or more of these conditions,
change the fuel brand you use. It will require at least one
full tank of the proper fuel
to turn the light off.
If none of the above steps have made the light turn off,
have your dealer or qualified service center check the
vehicle. Your dealer has the proper test equipment and
diagnostic tools to
fix
any mechanical or electrical
problems that may have developed.
Oil Pressure Gage
The oil pressure gage
shows the engine oil
pressure in psi (pounds per
square inch) when the
engine is running. Canadian
vehicles indicate pressure
in kPa (kilopascals).
OIL
- 1
Oil pressure may vary with engine speed, outside
temperature and oil viscosity, but readings above the
low pressure zone indicate the normal operating range.
A reading in the low pressure zone may be caused by a
dangerously low oil level or other problem causing low
oil pressure. Check your oil as soon as possible.
2-60