Originally Posted by BlackJohn
I'm wondering how Ospho would work on the innards of our radiators and heaters to loosen crud buildups? Remove any and all blockages, save removing rads, heaters etc.
Since you ask for thoughts,....no, I would not use ospho in a radiator. I think ospho is as the name would indicate, phosphoric acid. It is a rust converter, not remover. In other words, it will react with rust to form something more solid and seal it off.
There used to be a great 2 part product called #7 from Dupont. It was a fantastic product. I used it many times when it was available. It was a crystal form of an acid that I do not recall what type. And once the acid treatment was done, you had to neutralize it with the second product that came with the container.
Since we cant get it anymore, i have had actual reasonable luck with white vinegar. So far as I know or have been told, it does not need to be neutralized, just flush out of the system well. It is a mild acid that is very easily diluted and carried with water. The last vinegar flush I did was in a 74' chevy farm truck that would over heat as the inside of the radiator was built up with well water deposits. I removed the radiator and filled it with white vinegar. Let sit for a few hours, then agitate a bit by lifting the radiator side to side and let sit till the end of the day. Drained it, flushed it with clean water and reinstalled it the next morning. Filled with purchased distilled water and antifreeze. It solved the over heating issue and is still going strong today.
Your results may vary of course.