Re: alfa-digest V9 #310

[George Graves <gmgraves@domain.elided>]

Interesting, but  I must tell you that my research* indicates 
otherwise. If your car was designed to use multi-grade oil, then any 
multi-grade of the correct viscosity, including synthetic and 
semi-synthetic will work fine and will NOT damage seals and gaskets. 
The problem is that cars designed to use single-weight detergent oils 
(mostly built before the mid/late 1960's - depending on make) will have 
their seals compromised by any modern multi-weight oil, whether it be 
synthetic, semi-synthetic or pure mineral oil. Modern oils have 
aggressive additive packages, with strong detergents and dispersants. 
These are designed to keep all impurities in suspension so that they 
will end up in the oil filter, not in the engine. Older cars, with 
their single-grade oils depended on deposits around the gaskets and 
seals to make them oil-tight because the tolerances weren't that tight 
in days before CNC machining.  An aggressive additive package will 
dissolve these deposits and the seals will leak.  Also modern oil 
viscosity such as that found in synthetics is simply too thin to work 
in classic car engines. Oil suitable for a Milano Verde or a 164 will 
be problematical for the oil pump and bearings of a Giulietta. Owners 
of older Alfas like Giulias, Giuliettas, 2600s, and 2000s/1900s should 
use a modern single-weight mineral oil designed for "classics." These 
oils are formulated with less aggressive detergents and dispersants, 
but augment them with modern rust inhibitors, dry lubrication anti-wear 
agents such as molybdenum - which help with cold weather starting as 
well as viscosity index modifiers which keep the oil from thinning out 
to quickly as the engine heats-up.

*I just finished doing research for an article on oil to appear in the 
April "Overheard Cams" and these are some of the things I learned from 
such sources as Castrol, Red Line, and Valvoline.

George Graves
'86 GTV-6



On Monday, March 3, 2003, at 11:19 PM, alfa-digest wrote:


> Date: Mon, 3 Mar 2003 23:34:38 EST
> From: Iopsycheng@domain.elided
> Subject: Re: alfa-digest V9 #308
>
> Hey Gang,
> I've been reading about all the horror stories concerning oil leaks 
> when
> switching to synthetic oils. Please lets get something straight! 
> Synthetic
> motor oil DOES NOT CAUSE LEAKS, nor does it attack and/or degrade 
> gaskets and
> seals! Improperly installed, poor quality or worn out seals and 
> gaskets leak.
> Synthetic oil is very high detergent... If there were a small leak in 
> an
> engine eventually some of the solid contaminants carried in suspension 
> in the
> oil would find its way to the leak and become deposited. Enough 
> deposits my
> eventually seal the leak. This is how products like radiator stop leak
> actually work. Anyway, now the owner fills the crankcase with 
> synthetic oil
> and the high detergent capacity washes away the crud and presto! We 
> have
> leaks... Well, actually you always had leaks before, now you just know 
> where
> they are... I refreshed a 1957 Giulietta engine using many NOS gaskets 
> and
> seals. I have run the engine several weeks on Mobil 1, the garage 
> floor under
> the car is clean...
> If you intend on using synthetic oil it would be nice to do it early 
> in the
> life of the engine but I believe the wear saved by synthetic oil will 
> more
> than offset the cost of an engine gasket set, a tube of gasket sealer 
> and a
> weekend spent tinkering.
> Thomas Gonnella
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