48 ounces or 1.5 quarts.
You should always have 20 fluid ounces of oil in a Briggs and Stratton 5.5 HP lawn mower. This equals out to roughly 1.6 quarts.
check you tube under removing the govenor on a Briggs and stratton
40oz
Click the link and find your engine for the exact capacity.
SAE 30
RJ19LM champion.
10w - 30
48 oz
Most Briggs engines that small take 1 pint of oil .
SAE-30
Should take a Champion: RC12YC