Burning or Leaking oil? P0420 code - Cat issues?

Im going to put a piece of cardboard underneath the car to check on possible leak again. Do I just place the piece of cardboard underneath the engine or does the piece have to be big enough to cover the entire ground below the front of the car?

A mechanic told me that if the car is burning oil, that means the car is either done with or will eventually need an engine replacement. Do you guys agree?

What kind of hope is there if the loss of oil is just coming from a leak?

I will take the car to the mechanic this week and then decide on whether or not i want to drive 1,200 miles to use the warranty I have on the car.

Thanks guys

Read the warranty document, suppliers of used engines generally don’t warranty for oil leaks from seals or gaskets. Some require the front and rear crankshaft seals to be replaced before the engine is installed. Will the engine installer reseal the engine for free?

Before you can prove an oil consumption problem you must first repair the oil leaks, then an oil consumption test can be performed. Will they replace the engine because of oil consumption?

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By “ring job”, I mean removal of the pistons to replace the piston rings. It is not an easy undertaking, that’s why your mechanic states the engine is toast if it’s burning oil. It’s not economically feasible to have a shop do it and it’s pretty adventurous of a DIY project with risk of not succeeding.

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Dad had a 88 f-150 w/302 and lower miles and had warranty. Had oil burning issue. Ford replaced the valve guides and rings under warranty. 48 hr turnaround. I bet there were 211 parts in pile during job.

Basically, what you might call an engine overhaul.

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Guys, i want check again for oil leaks tonight. Where do i place the cardboard?

My piece isnt that big. Will it be okay if the cardboard is just directly underneath the engine or does it have to span the entire size of the front of the vehicle?

OK , so you don’t have a large enough piece of cardboard . Just put it in a different place for several days in a row .

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Go outside and look at the bottom of the engine, there should not be any fresh oil on or dripping from the engine.

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just put it under the main part of the engine. you can tape some sheets of printer paper to the edges of the cardboard to make it bigger. put some rocks on the paper and cardboard so the wind does not blow it away.
I would run the engine to operating temp. and see if it is leaking. then shut it off and let it sit and see if you see any spots on the cardboard. If you do see it is leaking, then I would jack the vehicle up and put it on jack stands. clean the bottom of the engine and let it run. then shut it off and look for where the fresh oil is coming from.

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I spoke to a mechanic over the phone and he believes the engine is burning oil. He said this because the cat only has 20k miles, and the code P0420 came up. He said this code wouldn’t come up due to an external leak.
Do you guys agree?

I wouldn’t write off the entire car just due to the engine burning oil. It simply means the engine isn’t brand new anymore. You can still drive it, but it will need more attention. Like regular oil checks and top off, as needed.

Yes, but…

The key question is HOW MUCH oil is it consuming?
The OP should have his mechanic perform an oil consumption test in order to determine the actual rate of consumption.

My friend’s Rav-4 had an oil consumption problem that only got progressively worse over a 2 year period, to the point where I was adding a qt to his crankcase every 250-300 miles, and the vehicle’s acceleration had become really weak. Amazingly, the cat never gave any indications of failing, but I knew that this was inevitable, and could happen at any time. So, I asked him if he was willing to spend big bucks to (at the very least) replace the cat on his then-13 year old car, and he decided that it was time to get rid of it. In order for it to be driveable on the highway, he would also have needed to overhaul the engine, and I think he made the right decision to dump it.

If the engine is “only” consuming 1 qt per 600 miles or so, then it is probably worthwhile to spend the money for cat replacement, but if it’s as far-gone as my friend’s Rav was, I would question how long it is practical to keep the car.