I don't do much , I'm not into additives. in the winter when temps dip I'll use Isopropyl in gas tanks but that's pretty much it.

from my snowmobile days. most sled manufacturers recommend running premix till you know the oil injection is functioning properly. you usually fowl plugs if you putz along . I used to run nitrous on one of my Polaris race sled. I took the oil injection off and went to premix to have better control of my oil/fuel mix and jetting.

adding oil to the gas, ambient temps, ethanol,humidity , atmospheric pressure and water grains all affect jetting
I find myself reading plugs and looking at exhaust temps allot in my tuning adventures

By MMO your talking about marvel mystery oil right.
It has a friction modifier like ATF some use ATF instead MMO looks alot like ATF
We used Justice bros engine tune up in the late 70's and 80's they had tests that proved it lowered friction to parts that rubbed from the friction modifier

one test they had a video of was back then they bought 25 used Datsun 510 and 610 cars out in Cal. and had them gone over so they all ran good with new oil 1/2 got the additive in the oil
Then took them to the salt flats and told the drivers to drive them as far as they could easily after the oil was drained
the no additive cars made it 3-5 miles
the additive cars made it 15 to 22
it was indedendently verified.

if you have ever changed and cleaned out the rear end diff on a limited slip
ZJ and forgot to add the friction modifier you will know in 2' of wheel travel