Well...I'd rather test stuff when the weather is getting warmer and they switch to summer gas (end of April?).
I'm doing the Motorsilk in the auto trans along with flushing in new synth ATF...having already done a partial flush with regular ATF from the original ATF with over 100K miles on it. Not exactly controlled testing. But I'm doing all this as much for longevity as mpg gain.
Through all this my driving at least remains more or less consistent...keeping revs around 1750 to 2000 for the most part. Top speeds 45 to 50. With the auto...you see an mpg jump when it shifts into 4th at 40 mph and locks up.
Seeing the nasty effects of too many stop signs and slow downs for curves etc....so maybe I just quit stopping and slowing down?
Not real likely....too easy to get t-boned.
I'm hoping to see a gradual avg mpg gain and a stable tank to tank avg of + 35 mpg this summer. Indications are a possible 40 mpg at 45-50 highway.
Interesting graph you have...but what is the part about draining a qt of oil...did you test overfilling by one qt? Or under filling?