I went to an auto parts store and the guy who was processing my catalytic converter cleaner for my 99 es300 (over 380,000 miles) suggested to use 91 octane instead of a combo of 87 gas and the catalytic converter cleaner. He claims it would clean the cat similarly or better than using 87 gas (which is what my car requires) and the cleaner combined. Is he correct? Im doubting his claim as he claims he has 2 people that use 91 for their old cars with high mileage, with one being over 200k.
For context, I use cat cleaner as I keep getting PO420 codes and I rather not spend money to buy a new cat. While its an emissions code, Im concerned it might mean my engine is burning too rich (Ive put my finger on the outer exhaust and did notice some black crud). I've been using cataclean for a few months and it seemed to have improve my engine idling, my car runs more smooth, and I am getting slightly better fuel economy (Yes i know its not a lot especially for this car but if its inexpensive then why not?). I also use cataclean to clean my piston heads, fuel injectors, O2 and the cat (obviously).
Is he correct?
suggested to use 91 octane ... claims it would clean the cat.... Is he correct?
No, that's nonsense.
rather not spend money to buy a new cat.
well at 26 years and 380k, that's probably what it needs. No amount of cleaning will erase wear and tear.
if its inexpensive then why not?
I doubt you made back the money you spend on the products.
I also use cataclean to clean my piston heads, fuel injectors,
I don't think that stuff is meant to be used long term. It's probably pretty harsh.
Catalytic converter "cleaner" almost never works. Changing gas sometimes, per Scotty, has been known to help but it has nothing to do with octane. In both cases it would only make a difference if the converter is just barely on the edge of poor efficiency. If a converter is in really poor shape replacement is the only fix.
Have you checked the other possible causes of the P0420 code aside from the converter itself? If your engine is running too rich that should show up in your fuel trims.
no sar you're supposed to run curry and drive past a 5 story building on main street
(inside joke, I know him personally)
but for real though, since I want to remain helpful on this forum instead of just leaving junk comments, I will leave my thoughts for anyone else who may come across this post. I do have friend who swears the only way to get his car to pass smog is to run a tank of 91. I have a similar car which didn't pass smog when I got it, and the mechanic ran cat cleaner and it did work, however it was along with fuel injection cleaner, decarbonizing the engine, and intake cleaner. they guaranteed it to pass and it did. that said, few things: 1. both of these cars are OBD1 so they're measuring tailpipe emissions and not reading codes like the OBDII car you have. 2. my mechanic is kinda in the hood and they guaranteed it to pass with said work... who knows maybe they just let it slide since they wanted to get paid. 3. I'm not sure if the cat cleaner he used was any different from the stuff you get at the auto parts stores.
