You need to be very careful. If you place yourself in the chain of custody of this material, you can become liable for it- and all the damage that it does. While it may appear to be grease, it's also industrial waste and a pollutant. If you take it and transfer it to someone who them buries it in a field, you could be liable for large sums of $$ in removing it.
The first step is the capacity of which you're acting- If you buy it as a reseller, that's one thing. If you charge to remove it as excess material or waste, the situation changes dramatically.
If you buy it and resell it, it's grease. If you charge to remove it, it's waste. You are now responsible for properly disposing of it. If you give it away, and that person pollutes with it, you have a problem.
Plus, grease isn't like used oil. It has much fewere and more complicated secondary uses. 4 tons of motor oil could be used in a waste oil furnace, for example. Grease has limited uses.
The MSDS is useless in determining what it is. A brand name or even better an API spec would point you in the direction of someone to buy it. The most importanmt thing- don't put yourself in a position of charging a dollar a pound to remove it, then having to spend 10 to have it removed from you.