There have been a 1000 posts and at least that many opinions here about Water Wetter. Here comes my independent diyer opinion.
I experimented with it, using the refill/bleed techniques specified for my engine. I filled the block about 1/2 way with 40% coolant & 60% distilled water which was premixed; then added a bottle of water wetter and finished topping off the block. I did this to ensure it was mixed in well with the coolant. Some have posted that they merely pour it in the expansion tank. I'm not sure that it would ever really blend in well with the rest of the mixture going that route.
Temp gauge readings remained as before. 87C or so on the road; 100C at idle in hot weather. Same ole same ole.
Some here have said that your temp gauge readings will not be affected. If that's so, how in the %^&$ does anyone know this stuff is really working? Yes I know Redline says it works and I would expect them to say just that.
Correct me if I'm wrong, but I've never heard any of the pro techs her endorse this product. If it was of real value, I'd suspect they would have said so. If any of them did, please point me at the thread.
My car has the M103 motor - SOHC. On this site and others, I've seen countless posts, all indicating what I mentioned above about temp. spread. The owners manual even says it's quite normal for these engines to get hot.
I think some of us are unduly concerned because we're used to Asian/Americam cars that read the same whether it's 20F or 100F oustide.
My 2 cents.