am buying a car from carhop. It’s half payed off. I came with a 18,000 mile or eighteen months warranty. I’very got plenty of time on my mileage but only six months on the eighteen months limit. It covers engine, transmission, and drive train. In the year I’ve had it twice has the low engine oil light came on. Both times I added oil to bring it to appropriate level. Recently my Cadillac converter was clogged. After watching a video on utube I was informed that either my car was running to lean or my engine was leaking oil and as the engine oil leaks it’s burning up and filling the Cadillac converter with crud. So I began to think I had found out why I was have ing to add oil in between oil changes. What can I have a macanic do to give me evidence it’s leaking. I no I have to pay for a new Cadillac converter because it’s not cover but as the warranty states there responsible for fixing the leak if it’s leaking or refund the money I’ve payed for the car if they think it’s cheaper the the repair costs. If they think they can screw me over they will try. I appreciate your time in reading this and any help you could give me.
am buying a car from carhop. It’s half payed off. I came with a 18,000 mile or eighteen months warranty. I’very got plenty of time on my mileage but only six months on the eighteen months limit. It covers engine, transmission, and drive train. In the year I’ve had it twice has the low engine oil light came on. Both times I added oil to bring it to appropriate level. Recently my Cadillac converter was clogged. After watching a video on utube I was informed that either my car was running to lean or my engine was leaking oil and as the engine oil leaks it’s burning up and filling the Cadillac converter with crud. So I began to think I had found out why I was have ing to add oil in between oil changes. What can I have a macanic do to give me evidence it’s leaking. I no I have to pay for a new Cadillac converter because it’s not cover but as the warranty states there responsible for fixing the leak if it’s leaking or refund the money I’ve payed for the car if they think it’s cheaper the the repair costs. If they think they can screw me over they will try. I appreciate your time in reading this and any help you could give me.
"Help keep the dealership from screwing me"
Sorry, but I fear that ship has sailed. You have to keep adding oil because the engine is shot. There is a chance that I’m wrong and it’s only a weeping valvecover gasket and/or weeping crank and/or cam seals, but I can’t tell from here. A shop will need to look at it.
To prevent it from happening in the future, you’ll want to have any used vehicle you’re considering thoroughly gone over by a reputable independent shop BEFORE you agree to buy it. Yup, it may cost you a hundred or two, but it’ll be well worth it.
You shouldn’t be posting your personal email address here
Seems kind of risky to me 
Exactly how much oil are you adding . . . to cut to the chase, roughly how many quarts are you using per 1000 miles
The P0420 catalytic converter low efficiency codes doesn’t always mean the converter is the problem, but if you’re really using a lot of oil, it might have damaged the converter, hence the code
Mind telling us what this car is . . .
Make
model
model year
mileage
Call me pessimistic, but I don’t think the dealer will refund the money you’ve payed for the car, because you’ve apparently already had it a year
If you aren’t already doing so . . . I suggest you check your oil level frequently, perhaps every weekend. Don’t get in the habit of not checking, and only adding oil when the red low oil pressure warning light comes on. If you let it get to that point, your engine oil level is already extremely low.
From the sound of it, your engine is not leaking oil, but is in fact USING oil. Does your warranty cover such a situation?
Low oil level or low oil pressure ? They are not the same thing
Catalytic converter
Youtube is not going give you definitive diagnosis. What you need to do is take the car to a mechanic of your choice, pay for a diagnosis and then see if the actual problem is something that is covered under your warranty.
Now it is possible there is an engine malfunction that caused the caddilac ie catalytic converter to fail. I would try the dealing with the dealer, maybe a bad engine component, an analysis by an independant mechanic may be worth the bucks, is this a reputable dealer?
“In the year I’ve had it twice has the low engine oil light came on. Both times I added oil to bring it to appropriate level.”
My Bonneville has a “Low Oil” alert, but it has never illuminated. I check all my fluids on all of our cars, weekly.
The fact that this came on (as long as it’s not Low Oil Pressure as @FoDaddy questioned) might not be a bad thing. How many miles were driven between refills?
I’ll have to look it up in my manual, but I think when it comes on (activated by an oil pan switch) you’re only down a quart of oil. It holds 5 quarts, so that leaves 4 quarts, plenty of oil. Keep it full, though.
What model-year?
How many miles on car?
CSA
Jennifer, fodaddy brought up a critically important point. Most cars’ oil warning lights don’t tell you when a quart needs to be added, they tell you when the oil pressure is low. This is an important distinction, because loss of oil pressure is deadly to an engine. Your engine’s critical bearings are lubricated by a barrier of pressurized oil forced through their spaces by the oil pump. If that pressure is lost, these critical bearing have no lubrication, no protection from running against one another at thousands of revolutions per minute and self-destructing. Your cylinders also lose their protective lubrication films and the piston rings can tear the walls up.
In your case it sounds like the damage is already done. But you absolutely need to get this vehicle evaluated by a reputable independent mechanic. There’s not much point fighting about the cat converter if the engine is toast. An engine burning too much excess oil will contaminate the innards of a new catalytic converter causing premature failure anyway.
I’m truly sorry, but IMHO you need to get this car evaluated by a reputable shop before putting any money into it. If the dealer will put the new converter in, go for it… then be sure the car is properly evaluated and post back. That may be your opportunity to move past it.
Please understand that I’m only trying to give you honest feedback. And a good once-over MIGHT prove my fears wrong.
The need for a quart of oil every six months for an old car is not unusual and not a indication of a failure. A catalytic converter replacement at this age also is not unusual. The car is getting old, enjoy it while you save money for a newer car.
An engine leaking oil will show oil on the outside of the engine or on the ground and it will NOT harm your converter. An engine burning oil will send oil out your exhaust pipe and destroy your catalytic converter.
You say you want help but you have not told us what kind of car and engine, the year and mileage on the car. the mileage you had to add oil at, how much oil did you have to add or whether it was a low oil pressure light like all cars have or an oil level light.
I would like to replie to the response in order. 1st to mountain bike, I appreciate your reply. Although whether the problem is what I suggested or and I’m not to sure, correct me if I’m wrong but whether the engine is blown (which I can still drive it the only reason I’m not is be cause the Cadillac converter it clogged and driving it would only make it worse. But if I change the converter and the engine continues to leak, burning the oil it will just cause the converter to clog up agian) or any of the seals aren’t functioning properly I would still be ok because I’m covered under the warranty and there responsible for the repair.
I would like to replie to the response in order. 2nd. I don’t use the Internet that much and when I made the post I really wasn’t sure I was doing it right. I kind of got it figured now. I can change the email but the help I’m trying to get is important enough for the risk. I appreciate the concern though.
133,000 milespecially when I bought it oil was full. 140,000 a year later. I’ve had to add somewher between 3 and 4 quarts in a year split between to times.
Pontiac, Bonneville 2003 133,000 when both 140,000 now
The warranty covers any problem with the engine, transmission, or drive train. If it’s a part of the engine I’m good. But stuff like the exact system, electrical system, ect ect. Would not be covered.
I really appreciate your post and help u seem knowlgeable. Would like your continued advice and opinions.thanks.
It may well be the cause. The oil burning may have caused premature converter failure. Without an evaluation of the condition of the engine it’s impossible to tell. Although Nevada made a valid point that converters eventually fail anyway. The contamination of the converter’s innards that causes its demise is cumulative, and even on vehicles that don’t burn excessive oil they usually eventually fail anyway.
Weeping of the gaskets that hold the oil in are “normal wear” too. Weepage of oil on an old engine is not uncommon.
The combination of all of the described symptoms is really what leads me to believe the engine is shot, and that cause or at least contributed to the cat converter demise. I sincerely hope that when the evaluation is completed it proves me wrong. But I wouldn’t want you to start pumping money into a car that’s in the twilight of its life.
I have to admit too that my bias against used car dealers, who get most of their cars from “closed dealer-only” auctions enters into my assumption too. Generally these are not top-flight vehicles.
I thank you for your post. It’s only my second car so I’m not the best with this stuff. I was born with only twenty % of my hearing, one of the many side affects is I can’t always pronounce or spell the best. I’m on disability so I am trying to find out as much as possible, which is why I’m here asking for advice not relying on utube. I have to make an informed decisions on whether to take it in to a repair man or the dealership. I only get 850 to live on in a month. Any help is appreciated in helping me come to a decision.
Whatever you can get the dealership to do for free under the warranty is to your advantage regardless of the decision you make when the warranty runs out. Go for it.
But if they start charging you, go elsewhere and have a thorough evaluation done.
The only caveat I’ll add is that knowing the car’s condition now might give you leverage to getting a refund, depending on exactly how your warranty is written and your state’s relevant laws.
I thought it was reputable. But I think there going to try to weasel out. If they did it would help me if I had to take them to court if I had 1 or possibly more unaffiliated macanic how testified that the problem is in a warranty Covered system. But I’m on a fixed income and making the decision to go to a macanic could hurt me finenatually. Try to ask for the advice so I can make the dissension.
When the warranty is close to expiring, take it to a shop that does a “pre-warranty expiration evaluation”. Cost a couple hundred bucks usually. They’ll look for problems that exist but maybe you haven’t noticed them yet. So you can get them fixed while it is still under warranty. They’ll usuallyl check for recalls and customer interest items too, to make sure you’ve get those done gratis.
During the times I added oil the dip stick was under the fill line.
2003 Pontiac Bonneville 133,000 when bought 140000 now can’t remember last milage between fillings
4 quarts in 7,000 miles is a quart every 1750 miles. I perform warranty repairs and no warranty company will approve to repair or replace an engine that has a consumption rate this low. If you can point out a leak that drips from the engine, that should be repaired but reasonable oil consumption is not a cause for repair.
The cause of the catalytic converter failure is no known, if it is clogged that is not a result of the oil consumption. An engine misfire will melt the contents of the converter and cause a restriction. Sometimes the substrate inside the converter will break apart causing a restriction.
There is no reason from the information you have given to believe the engine is “shot”, this car may last a very long time.
I was taught by my Father to check fluids weekly. 50 years later I still do it.