Instruct: Classify Amazon reviews into positive or negative sentiment
Query: worked once

after reading the reviews i bought this with some hesitation. i had the same affect as the other two guys. i pluged it in one night when the oil was warm and it didnt keep the engine warm but it kept the oil warm resulting in better oil flow for the first couple minutes of start up. the next night i went to use it again with the oil hot and the next morning when i pulled it out and touched it it was ice cold (0 degrees out). i tried it two more nights since then and it does not work anymore. next time ill buy one that goes in the lower radiator hose