im trying to slowly tune up a 2001 mazda protege 1.6 lx. 250,000 ish. i just took it on a road trip about 700 miles. can check engine light.. p0421 bank 1 this was my aunts car and always had it, nvr fixed. apparently they checked it, its a sensor.. but cheap to replace. now when i checked it.. they told me catty is shot. i dont mind to replace it, if i can figure out what is needed. i was about to oil change after road trip.. advanced auto said Full sy oil. and i noticed the sale in the paper and went for that. that worker said it would be better off mix blend. if engine has only used regular oil, Full sy will kill it. i got the mixed. got home to find my aunt only used regular oil... advanced auto has no oil in stock. i just went to a mech shop about oil change... 2 week wait??? tho the advanced auto worker also told me that there is no real difference in regular to sy.? is that true? just the weight matters? this is auto n it lags to change into gear, im trying to told it strong, advanced worker said to do a full flush, i thought that would kill it? i'm lost
should i keep to REGULAR oil or switch? i figure regular if thats what it has.
the code p0421 bank 1. sensor or catty?
flush tranny?
thanks
1) Use the type of oil and oil weight recommended in the owners manual.
2) It may very well be the cat. Just make sure your engine is running well before changing the car out. If the engine isn’t running well, like burning oil, then changing the cat will only be a band aid. But given the cars age, odds are the cat is shot. Make sure it is legal for you to change the cat in your state. Some states are more strict than others on the type of car that can go on.
3) Not sure what the tranny has to do with the codes. Is this a separate issue? I defer to the group on whether to change the tranny fluid or not. If anything change but don’t flush.
They guy working at the auto parts store is probably making $12 per hour and doesn't know a cotter pin from an allen wrench and he doesn't care. High mileage synthetic blend oil will works fine. That's what I use in my 40 year old truck because I can't get regular mineral oil like you.
thanks for the reply. ill keep to regular oil then. its cold outside, and most of my tools in storage (middle of move). so i may have to search for a mech if i can buy a catty. being in colorado, shouldnt be like heavy rust or so. and as for the tranny that was another situation 🙂 . ill have to learn about the group and the forum. thanks again for info. i just hope to fix everything asap, and let it just be reliable as possible