[Vwdiesel] Vwdiesel Digest, Vol 42, Issue 27

James Hansen jhsg at sasktel.net
Fri Apr 27 02:43:55 EDT 2007

Nope.  oil lubricates the cylinder wall.  The seal is effected by the
pressure in the cylinder pushing outward on the piston ring. Wear,
warpage, cracking, scoring all effect sealing, but oil viscosity
isn't really one of them.  Viscosity is more a bearing issue.
Thicker oil works better in bearings with less clearance.  Motors
built with close tolerances work better on thin oil- down to 0-40
synthetic. Older motors with wear and larger bearing tolerances can
make better use of higher viscosity oil.  Now that's just a rule of
thumb, there's other factors too...


paul lew wrote:
> I hope I'm not mixing things up, but I would think a thicker oil
> would create more of a seal from cylinder to piston ring. but yeah if
> the fuel is not burning fully or the engine has post nasal injector
> drip it would seep past the rings into the oil.
> Message: 2 Date: Thu, 26 Apr 2007 07:18:06 -0700 (PDT) From: David
> Cook Subject: Re: [Vwdiesel] Any Oil Analysis for xW-30 in a Rabbit? 
> To: diesel list Message-ID:
> <777241.64142.qm at web56501.mail.re3.yahoo.com> Content-Type:
> text/plain; charset=iso-8859-1
> How would the oil viscosity determine whether diesel can get into the
> oil?
> Seems like a one-way street to me and I can't figure out how the oil
> can determine what actually gets in there, seems like things like the
> rings are about the only thing that could allow diesel into the oil.
> Whenever I change the oil in dad's TDI, it always smells good to
> me... A little like a charcoal BBQ, but that isn't quite the right
> description either.
> David
> --- Stephen Kraus wrote:
>> Over time, the seals will begin to weep oil and the next time you
>> change your oil, best smell it. If it smells like diesel, time to
>> go back to 15w40... If I run anything lower than 15w40 the seals
>> leak and the oil mixes with the diesel. I notice no change in oil
>> pressure however. -- Stephen T. Kraus Jr. Home: (423)842-5890 
>> UB3RATL4Sf00 at gmail.com; 
>> _______________________________________________ Vwdiesel mailing
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> --------------------------------- Ahhh...imagining that irresistible
> "new car" smell? Check outnew cars at Yahoo! Autos. 
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