Re: Cats and Oil

[Richard Beels <beels@technologist.com>]

Zinc is a normal additive to oils.  Has been for quite some time.  Zinc
comes into play when the thickness of the oil film approaches zero and
there is metal to metal contact.The zinc compounds react with the metal and
prevent metal wear.  The quantity is something like 0.1 (zero.one)%.  More
zinc doesn't give "better" protection, the zinc level will last longer as
zinc is oxidized and will react with acidic stuff in the oil and become
depleted.  I would think your plugs would foul before a cat.  Kendall GT-1
oil has a high zinc content, Castrol was in the rest of the pack as I
recall (saw a chart somewhere).

At 12:49 PM 10/5/1998 ,  Todd Young was inspired to say:
>  Michael Bradley wrote:
>  
>  > I have a 94 90 Q with about 34 K miles. In August I replaced my LHS cat as
>  > it
>  > fragnmented and clogged up the works. Last week  the RHS  went. When I
asked
>  > the dealer what was the cause he said it was an oil problem. The
dealer has
>  > used
>  > Castrol GTX (as I have for years). Apparently it contains  a zinc compound
>  > that
>  > is hard on certain cats. He has switched to Castrol RX. Apparently Castrol
>  > is not
>  > unique here as any number of other SE grade brands also contain the
>  > same compound.  I have used Castrol GTX for yearts in other cars and never
>  > experienced a problem.
>  >
>  > Anybody with similar information?
>  
>   Interesting piece of info. Is this zinc compound listed on the bottle as an
>  additive, or is it just a nice little surpise you get when your cats fail?


Cheers,
	Richard
	88 90Q - <insert pithy witticism here>
	88 Golf GTi - PRO Rally