Hello everyone!
First off I wanted to share that I discovered this site earlier in the pursuit of trying to find an answer to a 8month old question regarding my motor oil. Which is, where is it going?! Also I'm not a mechanic by any means, but I do have technical knowledge and understanding of mechanics to a certain degree. Anyway, I hope I can present my situation clearly and get some more technical understanding from the more expert folks here. 
Basically my situation is this. I have a 2001 Subaru Outback wagon (2.5l 4cy engine) with 285,000 miles, that since last fall has been really eating the oil. To the tune of 2-3 quarts per every 3000 miles. I do not have oil flooding out on the garage floor here at home. Rather just a few drops here and there. Nor do I have blue or black smoke coming from the exhaust, or any smoke, at any time. The oil is just vanishing somewhere.
I have hung out in Subaru forums and the common agreement seems to be possibly bad/failing/gummed up piston rings. Or to a lesser degree, valve seal issue. I haven't gotten a leakdown test as no mechanic / garage has the equipment or the time to do it on a vehicle of this many miles. In fact, one shop said they didn't want to do it because "what do you expect happens with a car with this many miles on it?".
Taking time last fall I inspected under the hood and found a very oily/gummed up PCV valve and replaced it myself. The hose had oily residue inside of it. Leading me to believe pressure from the chambers might be forcing itself into the crankcase and that pressure pushing oil out to get burned off in the cat-converter. Of which the cat is giving me a check engine light P0420 error code.
*IF* this is the case, short of pulling and replacing the rings which is going to be expensive, are there any steps I can take to see if I can restrict the oil consumption? Are their oil or fuel additives to help in the event the rings are gummed but not actually failing? FYI, back in 2010 I had work done to replace leaking headgaskets requiring the engine to be pulled. They showed me the inside of the piston chambers and they were pristine. At the time I had maybe 205,000 miles on the vehicle. The crosshatching was fully visible, not a single scratch in the chamber walls.
If it helps, I've used Castrol GTX high mileage 10w30 or 10w40 oil over the years. I never had a leaking/consumption problem until about a year ago. There had been times where shops would use Valvoline or another brand (can't remember it) but never had any severe consumption issues. I've also used Techron fuel injector treatment, but after reading on here, that may not be the best to use...??
Anyway in my research Ive read that if the rings are just severely gummed up and not failing, this consumption can be reversed? True/False??
Also I did check my PCV valve again recently and to my surprise, it was just as coated in oil as the previous one was.
Any advice or input would be great! I'm really hoping it's not the rings as I really don't want to pay to have that done or even consider a re manufactured engine. Especially when I'm putting available funds into getting a second vehicle (F150).
Brad
Basically my situation is this. I have a 2001 Subaru Outback wagon (2.5l 4cy engine) with 285,000 miles, that since last fall has been really eating the oil. To the tune of 2-3 quarts per every 3000 miles. I do not have oil flooding out on the garage floor here at home. Rather just a few drops here and there. Nor do I have blue or black smoke coming from the exhaust, or any smoke, at any time. The oil is just vanishing somewhere.
I have hung out in Subaru forums and the common agreement seems to be possibly bad/failing/gummed up piston rings. Or to a lesser degree, valve seal issue. I haven't gotten a leakdown test as no mechanic / garage has the equipment or the time to do it on a vehicle of this many miles. In fact, one shop said they didn't want to do it because "what do you expect happens with a car with this many miles on it?".
Taking time last fall I inspected under the hood and found a very oily/gummed up PCV valve and replaced it myself. The hose had oily residue inside of it. Leading me to believe pressure from the chambers might be forcing itself into the crankcase and that pressure pushing oil out to get burned off in the cat-converter. Of which the cat is giving me a check engine light P0420 error code.
*IF* this is the case, short of pulling and replacing the rings which is going to be expensive, are there any steps I can take to see if I can restrict the oil consumption? Are their oil or fuel additives to help in the event the rings are gummed but not actually failing? FYI, back in 2010 I had work done to replace leaking headgaskets requiring the engine to be pulled. They showed me the inside of the piston chambers and they were pristine. At the time I had maybe 205,000 miles on the vehicle. The crosshatching was fully visible, not a single scratch in the chamber walls.
If it helps, I've used Castrol GTX high mileage 10w30 or 10w40 oil over the years. I never had a leaking/consumption problem until about a year ago. There had been times where shops would use Valvoline or another brand (can't remember it) but never had any severe consumption issues. I've also used Techron fuel injector treatment, but after reading on here, that may not be the best to use...??
Anyway in my research Ive read that if the rings are just severely gummed up and not failing, this consumption can be reversed? True/False??
Also I did check my PCV valve again recently and to my surprise, it was just as coated in oil as the previous one was.
Any advice or input would be great! I'm really hoping it's not the rings as I really don't want to pay to have that done or even consider a re manufactured engine. Especially when I'm putting available funds into getting a second vehicle (F150).
Brad
to BITOG...you will get comments and suggestions aplenty. Here's mine:
It does sound like oil is getting past the rings, as evidenced by 2 gummed up PCV valves in rapid succession and the catalytic converter code.
I agree with Donald that a compression test might be a good idea. However since that can be expensive and this is a sudden occurring problem I would try a good cleaner first and see if gummed up rings are the culprit. Worst off you will be is out an oil change or two.
I've used Auto-RX and on an older vehicle it worked as advertised. Many people here swear by Kreen or MMO, the choice is up to you. A good cleaning oil during these treatments would be a great idea also, so some PYB or your choice of a solid detergent oil IMO is indicated. Since you've used 40 weights, the 5w40 Rotella is 
Couple things: you said the shop did an oil change...well there have been several posts on here where the shop 
Please post back and let us know how it goes!!
