I have a 2003 toyota corolla s. 97500 miles on it. Recently my check engine light came on after I took it in to toyota for a oil change so I took it in and they said that I needed a engine fuild flush. I got that done and then 3 mths later I take it in for another oil change and then a couple days after the light came on. So I had it diagnosed for free this time and they told me that it was my catalytic converter. Could it have something to do with the oil that they change it with because both times have happened right after the oil change. Im planning on taking a 24 hr road trip and havenot gotten my cat. Converter fixed yet. How will that effect my car?