I thought I'd share my experience of this product. We were in southern Chile back in December last year when I noticed some liquid had collected on the left side of the engine - it appeared to be coming from the rear of the front cylinder's head gasket and was running down the block and onto the left-hand crankcase cover. It seemed to be coolant, and checking of the previously-full reservoir confirmed this.....it was almost empty. Being in a remote place, using some of the Holts Radweld Plus which I'd packed as an emergency measure was the only option. At this stage the bike had covered 54,500 miles. Anyhow, the leak stopped once the Radweld was added to the coolant. I kept a close eye on both the temperature gauge and the coolant level, with both remaining fine for the rest of the trip. The bike has now covered 9000 miles with the Radweld, and the coolant level has remained constant. The Radweld did its job very well. I'm debating what to do now we're back in UK. Holts technical dept say that the Radweld will go on doing the job permanently, or at least until I change the coolant again when I can either replace the suspected faulty head gasket or re-fill the coolant system making sure that a bit of Radweld Plus is added. Getting rid of the Radweld from the cooling system is apparently not difficult.....just flush it with plenty of water and an agent such as Holts Speedflush. Replacing the head gasket means taking the engine out of the frame. Whilst the head gasket appears the obvious culprit, I won't know for sure until the head's off. If I go down this route, I'll flush the old coolant and then re-fill with new, adding no Radweld. If the leak then returns, I'll be pretty certain it's the head gasket. Any thoughts....what would other folks choice be.....take out the engine and replace the head gasket or simply carry on using Radweld Plus? I'm sort of inclined to stick with Radweld whilst in Europe where there's easy recovery, but replace the gasket before going off again to properly remote places.