Someone else might post a better/clearer reply.
On GMC trucks, it can be interesting guessing the oil capacity. It seems that different sizes/uses of trucks had different oil capacities.
9.5 qts is possible/reasonable.
The easiest/surest way to find out is:
- empty the oil & oil filter (if you have one)
- add oil until you get a reading at the full-level/mark on the dipstick
- let it sit a few minutes, and check again
- add one or two quarts of oil for the oil filter
(at the oil filler or into the oil filter, depending on the type of filter and its size - close/seal the cap/top of the oil filter canister)
Start and run the engine for a few minutes until it is warmed-up, checking the oil pressure gauge.
If the gauge does not move/register-pressure, you have problems - stop the engine.
If you have pressure: after warming up, stop the engine; and, wait a few minutes.
Check the oil dipstick.
Add more oil, pint-by-pint as needed (stopping and checking after each pint).
