Testing Crown Power Amps with a Load Box

I need to test these for operation, I was told they work, but I know how that goes, since I did not acquire the speaker columns for a load, I need to build or purchase a load box, to test these, I was a ham once and realize I had a dummy load canister filled with oil to test ham radios, but would a dummy load can work for testing power amps too, I am not going to blow these amps up without knowing for sure how to test without a speaker load..once I know they are running, I either want to rent them out to bands or sell them..

that's right I own a
Crown XLS 202
Crown XLS 402
Crown XLS 602
Crown XLS 802
plus the rack plus the equalizer, power strip, and crossover

that's right I own a
Crown XLS 202
Crown XLS 402
Crown XLS 602
Crown XLS 802
plus the rack plus the equalizer, power strip, and crossover