glort high speed centrifuges are capable of separating isotopes from gaseous mixtures, this is how they enrich uranium.
https://en.wikipedia.org/wiki/Gas_centrifugeHow many G forces was your centrifuge producing, where you running cold oil or did you first heat the oil to improve its viscosity, which would encourage the water to drop out.
The deep fryer operates at temperatures well above the point of evaporating water which is evident when a basket of potatoes chips i first submerged into the hot oil.
The sizzle and bubbling only cease once the top layer of the chip has been cauterized sealing the remaining moisture inside.
Oil is lighter than water, increase the speed of your centrifuge and warm the oil before feeding it into the centrifuge the water has no choice other than to be liberated.
Also have you installed a water separator into your engine fuel system.
Bubbling air through your oil is no guarantee your going to end up drying the oil, air itself has a lot of moisture content.
I have a refrigerated air dryer from a retired dentist similar to the one below. Instead of passing air through the chill plate I'll be passing water used from my still condenser.