Instruct: Classify Amazon reviews into positive or negative sentiment
Query: completely worthless

I had used a a dipstick heater for a few years. I don't remember what brand it was but it did a satisfactory job. I misplaced it so I ordered a Kat's dipstick heater expecting similar results. I inserted the new heater into the crankcase and plugged it in. I came back a few hours later to check on it and it had burned out. Don't waste your money on this.