I had a water leak on my 2005 Picasso, so I took it to garage who had put a 2nd hand engine in for me. I thought perhaps a pipe or something wasn't right. The mechanic said it was the radiator, I mentioned a well known brand of sealant and he said he doesn't use it as it can cause the heater matrix to block. He had a scrap Picasso on forecourt said would replace mine with the one from there. He removed mine then I sat in the car while he installed the replacement I saw him pour something in from a quite small bottle. I returned home. The next morning I checked the water level to find it was my old radiator. When I called to query he said he'd told me which he hadn't but what got me is when I queried that he didn't believe in sealants he said what he used worked differently by welding the metal together and not blocking the hole like other products and that he paid over£20 for the small bottle. Because of the way it works it won't cause other problems. I am OAP female and I have searched web sites for this miracle fluid. Have I been conned. Also the engine warning light is on he said to ignore it it's saying EJR (I think that's what he said). The engine sounds and goes fine MOT is due this month would the light being on mean a fail. I am reluctant to go back to him unless you prove him right about the expensive fluid. If you have read all the way down this, thank you for your patience. In nut shell is there a sealant that doesn't use a gunge type liquid and will my car fail with engine warning light on. He has removed it twice but it comes back on.