Portland Refinery

So what happens to all that used oil—and could it be recycled?  The answer is, yes it can!

When you put motor oil into an engine, it is essentially degraded by heating it, and is also oxidized. As all these additives start to break down and the engine starts to wear more. As the engine wears it puts some heavy metals into the oil. The anti-foaming additive breaks down and you start to get water mixing with the oil and making sludge. The same breakdown happens with the dispersant and the detergent. That's the reason they recommend to change it every X number of miles because of the thermal degradation and oxidation. Oil only has a certain life span.

We clean that used oil by using pretty conventional refinery technologies. One of them is vacuum distillation, which dewaters the oil. Used motor oil comes with somewhere between 5 and 7 percent water in it. The first thing you have to do is get the water out of it.

Then we do wiped-film evaporation. This essentially separates out all the contaminants and additives that are put into passenger car motor oils. This process gives us a re-refined burnable fuel oil. 

If you're thinking of it in a very simple way, we're filtering the used oil with very sophisticated technologies and processes.