Instruct: Classify Amazon reviews into positive or negative sentiment
Query: cleans very well indeed

Didn't by it from Amazon; local stores and other sites sell it for less. Nevertheless, the stuff gets rid of corrosion wery well. I've had a huge growth on the negative terminal that'd spread to the cable (a technician had somehow broken the battery top around the negative post and acid leaked out) voltage drop in the clamp went up and starting was affected. Scraping alone didn't do a thing. BTC4 came and saved the day. It still took quite a bit of repeated spraying, scraping and rinsing, but in the end I've got the clamp and post shining.Following the instructions on the can is important. It is not enough to just spray and wipe; some salts are convertet into other salts that water dissolves (at least, this is how it looks). The reaction isn't instant, so be patient and give it the requested 5 minutes. Then scrape, or brush, or both; then rinse and repeat.