CRC Knock'er Loose Penetrating Solvent, 13 oz Aerosol Can, Reddish by CRC

Q: Why do so many more people seem to use and recommend pb blaster, compared to knock'er loose? is pb just hype or is kl actually better?

Its all opinion. But I am a 30 professional auto technician/shop owner and my opinion is KL or aerokroil is best. PB does great advertising.

Q: does this work on cast iron?

Not sure what you are trying to do, but we use the Knocker loose for rusted and hard to remove fasteners from various types of material, if you are having an issue with a bolt or some sort of fastener that you are trying to remove this product works great for that aspect,,hope this helps