I'm not really sure if there is a different between acrylic lacquer thinner and lacquer thinner and if I could use the acrylic lacquer thinner to unclog my catalytic convert.
My car has 90000 miles.
My car has an automatic transmission.
I am not sure who would have told you to clean or unclog the converter out with lacquer thinner, but that is not a very good idea, and you shouldn’t do it. The thinner may damage the converter internal material, as well as damage the oxygen sensors behind the catalyst. If the converter is clogged, the only proper repair would be to replace it. I do not recommend cleaning it out at all. I have been working on vehicles for over 20 years and have never heard of cleaning out a converter with thinner or any other liquid. Some diesel engines have an injection system that injects a urea based liquid into the catalyst when it is hot to burn off the carbon soot, which is different than what you would be trying to accomplish here. If you would like to have your catalytic converter replaced, then I suggest contacting a professional, such as the ones available from YourMechanic, to perform this for you.