I am non believer of Oil Additves. But i tried Liquimoly Ceratec in Prius 2007 and noticed following improvements. Engine becomes very very smooth. Increased Mileage +2 Km/Litre Engine noise is reduced alot under even extreme load. Acceleration is better by atleast 10% Please also post your reviews if you have used this product.
I've been using Ceratec for over 70k kms now. It's made by a very reputable company, one that actually sells oil, that company being Liqui Moly. I too noticed smoothness and quietness but saw no measurable mpg gain or acceleration gain that I could determine over time. My main reason for using Ceratec is to reduce wear on the engine. I've read some impressive used oil analysis data that some have posted over at Bitog and other forums. My goal is still to get 500k kms out of this car which I use for a livelihood doing deliveries. My oil change 26k kms ago I used Amsoil along with a couple of additives. I got 25K kms out of that oci. My most recent oil change I just did 1100 kms ago, after hearing about Edthefox5's positive results with Redline Oil and reading up on it, I decided to use it. I went straight 5w30 Redline with no additives. I have to say I'm very impressed with this true synthetic Esther oil. Smooth as silk, quiet, and a noticeable increase in acceleration as well. Redline claims "more power" due to it's ability to seal rings. Maybe it's true, idk, but I definitely notice an increase in power. No measurable oil loss in 1100k kms. It's also suppose to be good at conditioning seals. I'm so impressed with this stuff that I don't think I'll be using additives any more, though I do still have a couple of bottles of Ceratec that I plan to use. I've also been religiously using Lucas fuel additive as an upper cylinder lubricant since I bought the car. I've got 209k Kms and the engine is still running as strong as ever.
I don't think I've ever seen their Ceratec product on the shelves here in Australia, but I am using their MoS product. From what I can gather both products are supposed to work on similar principles, filling and smoothing the microscopic valleys and roughness on the running parts. I don't know for sure what other benefits they bring, but I'm pretty certain that these surface bonding lubricants do offer extra protection in the worst case scenario of loss of oil pressure. Back in the '90s I had an old mazda that had a total oil pump failure (I mean zero oil pressure), and like an idiot I kept driving (because I thought it was just a faulty sender). Absolutely no one has ever believed the distance that I drove that thing without the engine failing. Even the mechanic who replaced the broken oil pump was just shaking his head in disbelief when I told him. I was only running a plain old Castrol GTX mineral oil, so the only thing that I can put it down to is that I also had a tube of "molybond" in the sump.
I have not tried Ceratec. However, I have experimented with their better known "2009" product... a Molybdenum disulfide (MoS2) additive : I use it in our Hyundai vehicles and in the lawn tractor. It seems to 'make the engines run smoother'. However, this is obviously a very subjective observation. I was thinking of trying Ceratec in our 2010 but since it burns oil a bit...I'm not sure what unintended consequences it would have.