I remember Cataclean on it's initial release being marketed at independent retailers, and was backed up by some aggressive marketing in magazines and also commercials staring none other than ex-Anglia TV & QVC presenter Paul Lavers.
I've never used it, I've heard wonderful things about it.
But, like all things, there is a rub.
Should a catalytic converter "gunge-up", well, not really... That is to say that if a car is reaching operating temperature and given long good runs that the temperatures reached by a catalytic converter (ha) should make the whole thing pretty much self-cleaning to an extent. Not all cars get this treatment, infact I remember discussing this at the time as the aforementioned informercial as Mr. Lavers and a 'mechanic' took a rather tidy looking Rover 216 convertible (mk1) with average miles on it and did a before and after BET test as a comparison....
I believed the results on face value, but was this car being used on "around town" trips and never warmed up, I have no idea but my gut feeling was that this was the case.
Similarly the injector cleaners, Forté (which is marketed in a similar way, often direct to garage) and its counterparts have a great reputation and x-mpg improvement/quicker 0-60/more torque/less knock/improved windscreen visability is apportioned to them; I'm not disputing that but I don't think that for a lot of individual vehicles they prove a lot. An old sage of a mechanic I once worked with reckoned a cup of paraffin and some xylene cleaner in the fuel tank once a year worked best for his old Belmont....
**I'll once again be accused of being a witch or similar, but..**
I'm a firm believer in....
"A red-line a day keeps the mechanic away....."
A warm, thrashed engine with clean oil will last as long as the owner lets it.....
My 1p is always on 10k Boost, I've found this works wonders as an air-system cleaner on old diesels by the way....
As the old caveat goes 'your mileage may vary....'
Regards,
Andy