Oil burning before engine failure and catalytic converters

I'm building a house right now. I don't have much money I keep spending it on this stupid car.

I need it to last until I can get a better job.

The oil burning has been around 1 quart every 700 Miles. Now its about doubled its oil consumption all of a sudden. I put fresh Rotella 10w-30 T5 and it, burnt a bunch of that off and I added 8oz Lucas Synthetic oil stabilizer. 600 miles later, I'm about two quarts low. I added the other 8oz Lucas and one and a half quarts of oil. It does not leak a drop, has freshly gone through heads and head gaskets, new valve cover gaskets, new oil pressure switch, the works.

The car throws P4020 code for cat converter and I clear the codes and they come right back. I have to periodically drop the car into 4th on the highway and burn out the cat or they start to plug and the car runs bad. Takes a week or so of babying it to get there tho.

Is removing the catalytic converters recommended when it is burning oil that bad?

How bad does it burn it before there is a failure?

if you are burning a qt every 4oo miles,

your car will look like a smoke screen going down the road.

get on the ground and look for wet, oily spots on the bottom of the engine.

look for stains on the pavement where toy park.

these engines are notorious for oil leaks.

my guess is you have an oil seal, cam or crank, that has popped out .

this will cause a boat load of oil loss.

let it idle in the srive way and look for the drips.

buy several cans of ''brake clean'' from the parts store and spray off the bottom of the engine.

check it every day and see where the oil comes back first.

a clogged PCV will cause excessive oil consumption.

if you are ''burning'' oil, it will affect the cats,

but leaks are a much more common problem.

and the p0420 is usually an o2 sensor problem,

not a cat problem.

the rear o2 can be generic,

the front one MUST be from a subaru dealer ,

or better quality.

a cheap front o2 sensor will not fix the problem

and you will just have to do it over.

No smoke screen. The back bumper gets brown after a month or so of not being washed and its a white car so it shows easily. You can't see or smell oil smoke even on startup before the cats get hot. I drive this car pretty hard at times and I have only once seen smoke, and that was about three or so years ago.

Yesterday pulled the intake to flush the heater core, the heat quit. Minus 24 farenheight is not flipping fun with a barely working heater...There is not excessive PCV gunk in throttle body or pcv or valvecover vent hoses, the black cottage cheesy stuff that will plug PCV... Clean as a whistle. I change my oil too much probably because a lot of new oil goes in because of the burning, and I still drop it around 5-7000.

I will pull the PCV valve to see if the valve itself is sticking. I replaced my old PCV with a stronger used one about a year and a half ago while chasing a misfire.

I replaced the air cleaner to reduce vacuum on the PCV system.

I've replaced every oil seal sometimes three times (valvecover gaskets) until I bought Subaru seals, all except the oil pan and separator plate on the back of the engine because i didnt pull the engine to do the head gaskets this fall. The heads were checked and got new Subaru cam seals and valve seals.

I don't see any drips in the snow or in the garage when i pulled it in several nights for the brakes locking up because of rusty caliper pistons.

So if I'm not leaking it, and the PCV is OK, and I'm not Go go Gadget Smokescreen, what is the deal?

no smoke screen suggest you are not burning ALL the missing oil.

Yesterday pulled the intake to flush the heater core, the heat quit.

this does not sound good.

the heater quit blowing hot air.?

the fan blosws but the air is cold.?

if it happens again, in a few days / weeks,

check to see if the bottom radiator hose is cold.

this is a low coolant level indicator.

this COULD be caused by a bad head gasket.

it could also be due to improper filling the cooling system after you removed the intake manifold.

and a bad head gasket could also cause oil loss.

but this not common on a 99 ej22 engine so i doubt it.

and any mis-fire can cause a p0420 due to unburnt fuel in the exhaust.

because yours are #1 & #3, both on the passenger side,

you could have a timing issue.

check your cam timing.

so look at the oil and coolant for cross contamination.

mocha colored gunk in the coolant over flow bottle.

or the same in the oil.

look for a cold lower rad hose when you have no heat.

this is caused by not enough coolant,

you may need to burp the system,

or drain down and refill correctly.

how to fill and burp your cooling system. - burpcoolingsystem - Subaru Legacy Forums

you say it is not leaking,

is the bottom of your engine clean and dry,

no oily residue.?

the reason i ask,

these engine ALWAYS leak when they get old.

i used after market seals on my 97GT ej22 swap engine and had to replace them at about 30k miles.

like you i now buy suabru oil seals.

Fresh head gaskets and valve job this fall, all Subaru OEM everything except valve seals. If the o2 is on the passenger's side, I don't think it should be complaining, cyl 4 is the one that has problems and piston slaps. I have watched the o2 feedback on a scan tool and it looks like the o2 is performing just fine. I might try to pull it and clean it with maf cleaner.

Flush helped, heat works. Im a coolant burping vet. I've drained it more than 10 times at this point, getting tired of it lol...

I've timed this car 6 times now, and I do by counting the teeth on the belt after the marks line up and after turning it over by hand...

I will photo the engine sometime this week and check PCV.

If the oil burning will eventually wreck the cats, I'll get rid of them now before my house payments are out of sight.

About 400 miles and oil level is still OK. CEL has not come back and performance is good on 91.

I'm thinking a safe bet is that the dirty air cleaner was the cause, excessive PCV vacuum in addition to reduced performance. The cleaner was still translucent but wasn't snowy white like new.

I also have a full bottle of synthetic Lucas stabilizer in there.

38k until 300k... Come on baby hold together...