The excess ZDDP also destroys the O2 sensors. 

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Michael Snow
Sent: Saturday, December 03, 2011 6:34 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Vanagon engine noise - collapsed lifter?

Far better to use an authoritative source for this info:

http://www.mobiloil.com/Search/Search.aspx?site=mobil&output=xml_no_dtd&client=default_frontend&BCL=%2FUSA-English%2FMotorOil&la=en&km=mobiloil&show_km=y&as_q=inurl%3A%2FUSA-English%2FMotorOil&css=mobiloil&filter=0&ie=ISO-8859-1&oe=UTF-8&lr=lang_en&getfields=description&q=zinc&go.x=0&go.y=0

Our engines do not need zinc, they need phosphorous.  Zinc dialkyldithiophosphate (ZDDP) just happens to be the least expensive and most effective vehicle for delivering that phosphorous.  Zinc will damage the catalytic converter, and this damage is the sole reason for the reduction of ZDDP in the current crop of oils.  Oils with high ZDDP content are still available for racing and other off-highway use, where catalytic converters are not used.

Mike

On 12/03/2011 02:28 AM, Scott Daniel - Turbovans wrote:
> I personally can not say how much high zinc formulation oil can harm 
> or not harm a cat, but I bet the affect is very minimal on the cat 
> ....just my hunch.