Speaking of oil....is it possible...? | FerrariChat
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Speaking of oil....is it possible...?

Discussion in 'Technical Q&A' started by finnerty, May 1, 2015.

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  1. finnerty

    finnerty F1 World Champ

    May 18, 2004
    10,406
    #1 finnerty, May 1, 2015
    Last edited: May 1, 2015
    ....for a synthetic motor oil to either be so thin (low viscosity) or have additives / chemistries such that it can leak past "healthy" valve stem seals & guides and drip into the cylinders ?

    The reason I ask is that I just changed the oil in one of my daily drivers and all of the sudden I got some random misfiring and a bit screwy O2 sensor readings --- and a DTC for misfire set by the ECU. After checking through, and ruling out, everything else (fuel supply, ignition, sensors, exhaust, intake, emissions, etc.) I decided to pull the spark plugs (which were also brand new) and they seemed a bit oily but not too bad. I then decided to have a look into the cylinders with the scope, and I found what appears to be drops of oil on the tops of all the pistons ---- this was on a fully cooled down engine, of course.

    Now, I know this car's engine is in excellent shape and only has about 15,000 miles on it. Also, everything was running and performing perfectly before the oil change. The oil I used was not the OE preferred, but is a quality brand and was recommended as a suitable alternative by several sources. But, now I have some serious doubts about whether it is okay to run in this engine.

    I plan to drain it and re-fill with the OE preferred oil, and I hope that makes a difference and stops the leakage. The car is speced for synthetic and has only ever had synthetic in it --- so, I know it's not a dino-to-synth, or vice versa issue.

    I also do not suspect a crankcase vent / pressure problem because no related DTC's are present and there is no oil in the intake system.

    But, has anyone here ever heard of or experienced such a thing ? Or am I chasing ghosts here ?

    Because if it's not the oil, the next step may be having to pull the heads :eek:


    .
     
  2. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    9,741
    #2 Mitch Alsup, May 1, 2015
    What weight of oil was originally in the motor?
    How many miles on the original oil?
    What oil level was in the sump when you drained it?
    What weight of oil did you replace it with?
    How logn did you run the engine before taking the "second" look?
     
  3. Cribbj

    Cribbj Formula 3
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    Jan 1, 2011
    2,316
    Cooke City MT, The Coolest Small Town in America
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    John
    #3 Cribbj, May 1, 2015
    Mobil1 is well known for being able to sneak past valve stem seals, and some gasket material and finding or making leaks in cars that formerly had none.

    From personal experience, I owned a car that would suck Mobil1 past the stem seals & guides, so it smoked on deceleration, but it wouldn't smoke on dino oil.

    Some attribute this to synthetic's better detergent additives, which purportedly clean sludge and other deposits, however there are some synthetics that are supposed to "help" worn stem seals to seal better, but I can't remember who? Castrol perhaps?
     
  4. 2NA

    2NA F1 World Champ
    Consultant Owner Professional Ferrari Technician

    Dec 29, 2006
    18,221
    Twin Cities
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    Tim Keseluk
    #4 2NA, May 1, 2015
    I've used a lot of Mobil 1, I've never experienced increased consumption.

    My 98 Volvo smokes briefly on startup. I've assumed it was from the turbo on the 155K motor.
     
  5. tomberlin

    tomberlin Formula Junior
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    Apr 9, 2005
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    Bethesda
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    tom berlin
    #5 tomberlin, May 1, 2015
    Sorry if I missed it in the post, but what kind of car is it?
     
  6. Arnie

    Arnie Formula Junior

    Oct 5, 2011
    465
    New Jersey
    #6 Arnie, May 1, 2015
    could you possibly overfilled it? That would cause your problem. When you drained your oil are you sure you got all of it out.

    As for Mobil 1 that did occur years ago when engine tolerances were not as tight as they are now. So it is not Mobil 1 problem unless you have an engine problem. Have you done a compression or leak down test?
     
  7. finnerty

    finnerty F1 World Champ

    May 18, 2004
    10,406
    #7 finnerty, May 1, 2015
    It's funny you mention this...... Castrol vs. Mobil 1.

    I actually have the opposite scenario.

    Before the oil change, the car had Mobil 1 5W-40 in it ---- no leaks, no problems.

    At the oil change, I put in Castrol Edge 5W-40 ---- now the leaks and the fouling plugs.

    Mobil 1 5W-40 has become hard to find, so I may try Mobil 1 5W-30 or 5W-50 instead.
     
  8. scowman

    scowman F1 Rookie

    Mar 25, 2014
    2,550
    Scottsdale AZ
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    Stu Boogie
    #8 scowman, May 4, 2015
    Another oil thread. I Love it��
     
  9. fatbillybob

    fatbillybob Two Time F1 World Champ
    Consultant Owner

    Aug 10, 2002
    29,212
    socal
    #9 fatbillybob, May 4, 2015
    I have never seen a modern obd2 car without oil in the intake system. That's where the blowby goes. All cars have it and the cr@p is sucked into the intake and burned yet puddles in low altitude places in the intake.
     

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