Some of the major saw companies buy B&C oil from the same supplier.
It's the same, except for packaging, color, and price.
I know, because I sell it under different brand names.
Tractor trailer load went to a Stihl dealer, because of the high quality, and price. Different name brand.
The 'Wally World' oil under the Poulan (green bottle-not black&gold) isn't always consistantly the same exact viscosity (30#-Summer blend). But at less tha $3/gallon. It won't hurt the B&C.
Some test results year ago were something like (abbreviated):
B&C vs Motor Oil
Viscosity: 30# vs 30#
Quanity used: 1 quart vs 4+ quarts
Run Off Puddle: Small vs Large
(Saw at idle)
(saw off)
Wear: "Normal" vs Accelerated
(B&C)
Chain Stretch: "Normal" vs Accelerated
(72 link) (Almost could remove a drive link)
Economics: Very Good vs Poor
Average Retail: $3.99 vs $2.99 X 4 = $11.96
(gallon) (took 4X's more)
That didn't include cost of accelerated B&C wear
USED MOTOR OIL
VERY, VERY bad biologically. Lots of extremely harmful byproducts
Remember,....there is a very fine mist/spray of oil droplets..........
YOU ARE BREATHING......INHALING THEM !!!!!!!!!!!!!!!
Not to mention it lubricates much worse than plain motor oil.
But, it's great for the parts, and service business.
Filters can clog easier, oil pumps wear out faster, chain stretch more, etc., etc.