2011 legacy 2.5i prem engine troubles

[Saberwolf]

hello guy's i am having a bit of trouble with my car.

 

don't know if i need to rebuild engine in about 6,000 miles i lose 2.5 quarts of oil and my yellow oil light come on i have slowly over time lost fuel mileage i would be 34 - 38 amgp now i am struggling to get 28.

 

bought the car in 2017 with 108k miles on it, two day after i buy it car over heats going over I80 to Sacramento CA. take it back to dealer and they replace head with remains fuel mileage is great at this time year and a half later i start to notice fuel MPH go down. then i blow a passenger cam oil seal in the rear of the heads from this day forward it starts to eat oil. i can usually tell when i need to add oil by the engine and my MPH. still struggling to get my fuel mileage back to where it should be to this day oh all repairs have been done at the litha dealer ship. with the exception of the remain heads that where installed by A-1 transmission witch took them a freaking 2 months to rebuild the heads.

 

current day 5/8/2019 i did compression test results are as fallows

 

Cold no oil added to cyclinder

 

left side front bank 165

left side rear bank 167

 

right side front bank 172

right side rear bank 168

 

warm no oil added to cyclinder

 

left side front bank 170

left side rear bank 179

 

right side front bank 175

right side rear bank 170

 

Warm with oil added to cyclinder

 

right side rear 195

right side front 190

 

left side front 195

left side rear 195

 

 

any help if i should rebuild engine or any other test to see if it needs it

 

took it to dealer on the complaint that it was eating oil they said it needs new engine

 

this did not sit well with me so this is the reason i am posting this on the forums to day

 

i do not know how to do a leak down test i am assuming you are applying air pressure to cylinder when it is TDC and check to see if it is leaking by.

 

i don't have any specs for compression i have heard 150 - 185 with a 7 psi difference but i am guessing at this point

 

let me wrap this up my car has 168k miles on motor bottem end about 60k on heads it has blow out rear cam oil seal and currently eats 2.5 quarts every 6K. also had the transmission manifold replaced with the wiring harness.

 

any suggestions would be helpful

Thank you, for your time and effort.

[Darth SpecB]

The compression numbers look sufficient. Your plugs describe your cylinders as running lean.

 

You should check for fuel pressure to see if your getting enough. Definitely replace those plugs, clean your maf sensor, and throw a fuel system cleaner in the tank. Also change air filter.

 

2.5 quarts every 6k miles with a leak isn't too bad. You should be changing your oil every 3k. And check/fill oil everytime you get gas.

 

Start saving up for a replacement engine, or at least address the cam seal leak.

 

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[Darth SpecB]

For a leak down test you charge the cylinder with air through spark plug hole. Make sure the intake and exhaust valves are closed. Turn engine over accordingly with crank pulley. If you hear air coming out of intake piping or exhaust, then you know your valves aren't seating.

 

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[dgoodhue]

I would replace your PCV. It could be causing your oil leak and some of the oil consumption.

[FaderUS]

I have the same car, and it was using far more oil than yours before Subaru decided it needed a new bottom end at 87k. I don’t remember the specific threshold but it was in the neighborhood of 1 quart per 1k miles. I have had many cars from classic muscle cars to Porsche and if I lose less than 1 quart before a 3k-4K oil change I don’t consider it a problem.

 

The low oil light should never be used as a signal to add oil, it triggers far too late.

 

 

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