How much oil to put in a 6.25 briggs and stratten

BRIGGS & STRATTON ENGINES:
For temperatures above 40? F use an SAE30W oil. Using multigrade oil may increase oil consumption. Using SAE 30W oil below 40? F will result in hard starting and possible engine
bore damage. For temperatures below 40 ? F use
an SAE10W-30 or SAE5W-30 oil. Oil capacity for the 6 H.P. engine is approximately 5/8 quart (20 ounces; 0.6 liter).
Refer to Briggs & Stratton engine owner's manual for additional
information.

2 quarts with a filter.

http://www.stripmine.org/sears/engine/briggs_older_engines.pdf

Find Your Operator Manual Briggs Stratton Go here to get the maintenance manual for your engine.

How old is the fuel? Drain old fuel, use premium fuel and change spark plug and maybe air filter. I start mine in the Spring using quickstart. It also starts and dies a few times and eventually keep running. Winterizing the machine in the Fall prevents most starting problems in the Spring. If this does not solve the problem, see a mechanic.

How does it run? Is it back firing through the air filter box area? And although your stating it is oil is it actually oil or gasoline that is black due to getting dirty? Don't shoot me! I'm going on what information I'm reading what you submitted. If oil is it enough to show up quickly on the dipstick/engine oil level ? Get back to us and we can go further.

White oil in any motor indicates the oil has mixed with water . Drain the oil change the filter and find out how the water got in.

Workshop (repair) manuals are available for ALL of the Briggs and Stratton engines. They usually cost money though. The free downloads are only for the owner's manuals. You can do a search for Briggs engine repair manuals. There are many, many of them available.

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwjPwu3B5YH9AhVqkYkEHRwKCAIQFnoECAUQAQ&url=https%3A%2F%2Fwww.fixya.com%2Fsupport%2Ft5979403-troy_built&usg=AOvVaw0b3wiQJvQu7Er6dxxb4OY8