I have a 2000 SE that I just bought a couple months ago and I changed the oil about 1200 miles ago. I have the p0420 code with a clogged precat and sometimes I do see some smoke behind me blue and grayish after getting off the freeway and sitting at a light, when I take off is when I see it. Anyway, drove up to Seattle yesterday, about 30 miles, and on the way home I was in and out of stop and go traffic plus it was about 90 out with the AC on full blast it would start to over heat after 10 or so minutes of barely moving. Also if I let it drop to idle the oil light would flash but if I kept it at 1000 rpms or more it wouldn't. When I turned AC off the car would cool off. So I got home and check the oil and it was dry. I added a quart, still nothing, then another, still nothing, then after about 3 it showed up at the bottom of the stick. I decided to wait and run it and let it drain back down before adding more but haven't done that yet.

I have heard that having the cat clogged can cause it to burn oil, I remember reading that somewhere on this forum in all the searching I did on the P0420. The car only has 123k on it and it did get parked and hardly driven for about 1-1.5 years before I bought it.

What can explain it burning 3-4 quarts in 1000-1200 miles?

Car runs smooth and drives good, even when the oil was that low it still didn't miss a beat.

Your thoughts are appreciated as always,

thanks

Joe

 

3 liter engines aren't known to be oil burners like the 3.5's are. If you are going through that much oil there's probably an internal problem somewhere, such as worn piston rings.

Get a compression check done.

 

I burnt out almost the same amount in two weeks and never found out why. No oil spills or signs that it sprayed out while driving but it was all gone

 

Head gasket? You'd have to be WOT a lot to burn that much even with toasted rings, I would think.

Now, for a burning/leaking 3.5 and hard driving, that's easy to do

 

since the cat is clogged and car doesn't have much power I am pretty easy on it, hardly ever going past 3500-4000 rpms. I had a mechanic do a full inspection and they are the ones who changed the oil. No leaks or anything, and car runs fine, gets 23-24 mpg.

 

Here you contradict yourself - first you said that 'I changed the oil' implying that at list you looked at the stick at that time and now it turns out it was your mechanic. To state that car 'burns oil' you have to monitor the oil level yourself and only then jump to conclusions. What if it was not full to begin with?

Regardless of what happened you better watch it now as you almost killed your engine.

 

I had to spend $150 to get a waiver to pass emissions so I could register the car so since the cat replacement at a shop was big bucks he just charged me $150 for the diagnostic so I could get the waiver. It sucked paying but didnt have a choice at the time, and so I didnt feel completely like I wasted $150 I asked him to change the oil for me. I had bought the stuff to do it myself but hadn't yet. It was full after that and was planning on checking before the trip to seattle but forgot.

I added 3 quarts and it needs another one probably so I will keep a closer eye on it now. Just hope I dont have to tear apart the engine because if it keeps burning it at that rate i should start investing in some oil companies.

 

I hate to tell you this but for the benefit of others- replacing cat as a consequence of 'failed' smog test is easy and useless fix. The not so honest shops simply don't bother to bring the cat to the operating temperature and claim car 'failed' conveniently offering to replace the cat. After replacing the cat they do let it warm up properly so it 'passes'. This is from my own experience - the same car was all over the charts one day x10 times and more on multiple parameters and almost passed (2 units more than norm) on single parameter the very next day at a different shop. If I had time I'd probably find one which would pass it.

I'd really start looking for another shop if I were you, you might lose a lot of money at that place. In my experience, this kind of places suck at repairs as well so you end up being double screwed: overcharged and under- serviced.

 

I don't have a shop, I usually do most of my work myself and if its too big of a job and not worth my time I have a backyard guy Ive used for 15+ years and trust with anything. Unfortunately to get the waiver in washington state you have to spend $150 at a emissions certified shop diagosing or repairing the problem. I am a UPS driver and this shop is on my route and I know the guys fairly well. Its a good place. The shops don't deem it pass or fail anyway.

I knew from hours of reading about P0420 and wasting money on an O2 sensor, that since I have a Fed Spec car I can get a y pipe and fix the problem. Due to a time limit on registering the car I had to go the waiver route to get it registered. I didn't have time to order Ypipe and install. So the shop did their $99 full car diagnostic and he just charged me more to get me to the $150 mark so I could register. He didn't pull one over on me or anything I knew what was going on and I hated but didn't have much choice. I had 15 days to register car and then get hit with $50 fees.

 

Don't forget.

My number one rule when purchasing a used car is to watch the oil level religiously for the first few months of ownership, so that if it uses oil, it is quickly replenished. I can then establish a trend of when (operating conditions) and how much oil is used.

Just my $0.02

 

So how long do you think you were driving around with oil that low? Chances are you have some internal damage now driving with 1qt of oil. All the cars I've seen that get that low, have been that way for some period of time and develop rod knock in the motor and some sort of ticking.

 

I had someone drive my car today while I followed so I can watch the tail pipe and pretty much at every start and every shift it smoked. Just little puffs. Also while accelerating there was very little sometimes but written cruising there wasn't any. Is the engine pretty much toast? That means bad rings right? That basically means an engine rebuild doesn't it?

Just doesn't make sense with 120k on it.

 

bump

 

Any oil in the coolant? I'd drain/fill the cooling system just to see. That would tell you where the oil is going fairly quickly - whether it's head gasket or rings.

Could also be a combination of the above, and/or an external leak like rear main seal.

 

So I replaced the Ypipe today and found that it was my main cat that was messed up. It was in peices with a whole down the middle of it, and the steel mesh was plugging the whole. So now with the new Ypipe I am pretty much running with no cats and smoking is prob 2-3 times as bad. Car has power now and I'm going to monitor the oil usage.

Question is do I just swap in a new engine or tear it apart and replace rings and whatever else needs it.

 

Also will an ebay high flow cat help with keeping some of the smoking down? and in the last 400 miles or so I've had to add another 2 quarts

 

did you carfax this car?it might have 223 rather than 123 and depending on previous owner thiws might be the reason they sold it,

 

there's no reason one of these cars should burn that much oil at that mileage, unless it was badly neglected and abused.

 

my 95 doesnt burn a lick of oil and it has 130k on it.

 

4th gens are not known to burn oil. 5.5 gens are.