Re: Quattro Digest V3 #81

[Robert King <rking@earthlink.net>]

Dan,

I don't think the Mobil 1 had anything to do with it.  Your motor must have
been going south and the Mobil 1 may have just made the symptoms a little
more noticeable.  Have your mechanic do a compression test on the cylinders.
If there is a huge amount of leak-down, then either the valve train is worn
or the rings/cylinder bore have worn.  

I put Mobil 1 into my Audi 80 Quattro after I purchased it with 103,000
miles.  It runs great on Mobil 1, though I use the 10-w-30 oil.  The 5-w-30
shouldn't make an appreciable difference.  Anyway, if you've lost the
electrode on a spark plug, you've got to consider detonation.  I haven't
been on this list long, so I don't know what kind of Audi you have (turbo or
non-turbo) but detonation can happen from any number of reasons... from low
grade gas to timing that's too far advanced (forming a hot spot and burning
off the electrode).

You also said that the car ran fine for 2000 miles then died.  After taking
out two of the plugs and seeing that they were oil soaked and seeing one
with a burned electrode, I would guess that you're experiencing excessive
oil fouling from valvetrain or cylinder ring leakage (probably valvetrain
though) and that the other cylinders were working harder to compensate (thus
the excessive heat and burned electrode).

So... have your mechanic do a compression test.  This should really say
something.  (Remember that you don't want over 20% difference in compression
between the highest and lowest reading!)

Bob
88 Audi 80 Quattro
95 1/2 Isuzu Rodeo LS
94 Ford Mustang SVO
>------------------------------
>
>From: Dan Simoes <dans@ans.net>
>Date: Tue, 30 Jan 1996 14:27:03 -0500 (EST)
>Subject: need big time help
>
>OK folks.  The mechanic just called and this is his take on the
>smoking/misfiring engine.  I had switched it to Mobil One 5w30 
>with factory filter about 2000 miles ago.  He thinks that the Mob1
>is too thin for the engine and that it "queered" the engine.
>Basically oil was getting into the cylinders and causing it to 
>run rough, and ultimately a lot of oil, causing it to smoke
>excessively.  He says my only options are a) rebuild and b)
>replacement, he recommends the latter.
>
>I suggested flushing the engine and running a thicker oil, 
>because as I pointed out, none of the engine tolerances should
>really have changed.  He's going to dump some 10w40 in and see
>what that does and call me back.  Does this make sense?  
>
>I guess I'm looking for feedback overall.  Is this a possible
>scenario?  He claims he's seen several engines do this on Mobil
>One.  If so, Mobil's footing the bill for this if I have any say
>in the matter.  I also wonder why it ran fine for 2000 miles or
>so then suddenly did this.
>
>Postmortem... he just called and reports that the #1 and 2 plugs 
>were soaked in oil, but #3 was dry and... the plug tip was ripped 
>out.  His guess is low oil pressure.  At this point, he said it's
>not even worth putting oil in the engine.
>
>Oh, and that half-joke about sticking in a turbo engine?  He said
>the conversion runs about $6000 total.  A standard replacement
>should run $500-800 for the motor and 15 hours of labor ($900 
>at $60/hr).
>
>Sigh...
>
>| Dan |
>- -- 
>Dan Simoes			          dans@ans.net
>ANS 				http://coimbra.ans.net/dans.html
>100 Clearbrook Road  			(914) 789-5378 (voice)
>Elmsford, NY 10523			(914) 789-5310 (fax)