This maybe of Help ?

Hi all,
I have a '96 Toyota Hi Ace Multi Van, Auto, 2.4 Motor & on Gas as well. 283000K's + -.
About 2 1/2 yrs ago I had a problem with my Radiator. Would do, say, 450K's. & would use up to 5 Litres of water, & stopping every 65 K's. to fill up.
Tried some Sealing Stuff, didn't work.
Then a young chap said to try " CarGo, Metallic Seal-Up ". It has Copper Filings in it. $9.90 @ Repco.
Absolutely worked to Perfection.
Done a trip of 375 K's. recently & used about 1 Cup of water, & had the A/C going.
I have nothing to do with Repco.

Egg white or ground pepper work too.