Very few oils are actually established to possess antioxidant properties. Most oils in fact, particularly vegetable oils, are rancidity prone, and have pro-oxidative effects. The oils that have the most pronounced anti-oxidant effects are the most stable and least rancidity prone. Both Extra Virgin Coconut Oil, and Ratite (flightless birds, i.e. Ostriches, Rheas, and Emus) oils top the list. Extra Virgin Olive, although much less stable, does possess a slight and transient anti-oxidant effect if extracted properly.

       Among the Ratite and other oils extracted from Avians (birds), Emu Oil exhibits the highest level of anti-oxidant activity, which may at least partially explain the hair growth stimulation effects unique to this oil. This study not only validates the superiority of Emu Oil in terms of its anti-oxidant properties compared to other oils, but also denotes important variables that effect the degree of anti-oxidant protection that any particular Emu Oil may confer, which has direct implications for its effectiveness in stimulating hair growth.

      These variables were alluded to by Dr Holick years ago in his groundbreaking patent application detailing the hair growth stimulation effects of topically applied Emu Oil. The primary variables of concern were rendering (melting) temperature of the fat pad and diet of the Emus.

Comparison of the Antioxidant Properties of Emu Oil with other Avian oils
Darin C. Bennett , William E. Code , David V. Godin and Kimberly M. Cheng 
Australian Journal of Experimental Agriculture 48(10) 1345-1350

The antioxidant properties of emu oil were compared with oils derived from the fat of other avian species. We first examined their free radical scavenging activity against the 2,2-diphenyl-1-picryl hydracyl radical. The concentration of emu oil in the test solution that caused 50% neutralisation (IC50) was variable (24.5 ą 5.9 mg/mL, range 5.3-55.4 mg/mL), but similar to values obtained for other ratites (10.7 ą 5.9 mg/mL). In contrast, the IC50 values for duck and chicken oil were much higher (118.0 ą 8.1 mg/mL). The variability in the radical scavenging activity of emu oil preparations may reflect variations in the diets of the birds, the processing protocol and/or the storage age of the oil. We also evaluated some of the ratite oils for their inhibitory capacity on human erythrocyte membrane oxidation, by measuring the reduction of the thiobarbituric acid-reactive substance (TBAR) production. Emu oil had a greater effect in decreasing TBAR production than either the ostrich or rhea oil, suggesting that it offers more protection than the other ratite oils against oxidative damage. In conclusion, we demonstrated that emu oil has both antioxidant properties in vitro and a protective role against oxidative damage in a model biological membrane system. The antioxidant or radical scavenging properties of emu oil appear to be due to minor constituents in the non-triglyceride fraction of the oil, while its high ratio of unsaturated to saturated fatty acids offers protection against oxidative damage.
When temperatures used to melt the fat pad from which the oil is extracted are too high, it has a negative effect on the molecular bonds of the oil, and can compromise it’s anti-inflammation effect, which is the method, in addition to 5 alpha reductase inhibition, by which it stimulates hair growth.
In most Emu ranching operations, Emu is raised for its meat, and the oil is simply a profitable byproduct. Virtually all Emu Oil produced in the United States, including that which is American Emu Association (AEA) certified, and most in Australia, is rendered at high temperatures, due to the convenience and speed of production.
Another factor which significantly impacts anti-oxidant, and thus anti-inflammation potential of Emu Oil is the diet consumed by the Emus. The vast majority of ranches use, again for the sake of cost, convenience, and weight gain, grain based diets(primarily corn), which produces an oil with a fatty acid profile that is less than ideal for both the health of the birds and the therapeutic benefit of the oil. To optimize anti-inflammation effect, it is best to have Emus free range roam and consume food from the natural environment, which results in high levels of lignans and anthocyanidins in the oil. 
The Emu Oil we make available from MPB Research is from Australia, and is by design, both low temperature processed and from Emus that are free range roaming. This is why many who have tried Emu Oil in the past with no success, experience hair growth stimulation when using this oil. 
Even Emu Oil that is from free range roaming Emus that is low temperature processed is a remarkably cost effective intervention. When used concurrently on facial skin, it produces an anti-aging effect that is comparable to the stronger concentrations of Retin A and Tazorac.