GMC 1998 Savana Van Owner's Manual page 254

Be sure to fill it enough to put the level somewhere in
the proper operating range. Push the dipstick all the way
back in when you're through.
What Kind of Engine Oil to Use
Oils recommended for your vehicle can be identified
by looking for the "Starburst" symbol. This symbol
indicates that the oil has been certified by the American
Petroleum Institute (API). Do not use any oil which
does not carry this Starburst symbol.
If you change your own
oil, be sure you use oil that
has the Starburst symbol
on the front of the oil
container. If you have your
oil changed for you, be sure
the oil put into your engine
is American Petroleum
Institute certified for
gasoline engines.
You should also use the proper viscosity oil for your
vehicle, as shown in the following chart:
RECOMMENDED SAE VISCOSITY GRADE ENGINE OILS
FOR BEST FUEL ECONOMY AND COLD STARTING, SELECT THE LOWEST
SAE VISCOSITY GRADE 011 FOR THE EXPECTED TEMPERATURE RANGE.
HOT
WEATHER
COLD
WEATHER
LOOK
FOR T H I S
SYMBOL
00 NOT USE SAE 2OW-50 OR ANY OTHER
GRADE OIL NOT RECOMMENDED
6-14
.