[T3] ZDDP: How much is too much?

[Brent Bottolfson]

This is from the Valvoline website:

Which oil has more zinc/ZDDP: VR1 or "Not Street Legal" racing oil?

Valvoline VR1 Racing Oil contains .13 percent of zinc and .12 percent of 
phosphorus compared to the Valvoline "Not Street Legal" Racing Oil which 
contains .14 percent of zinc and .13 percent of phosphorus.

I've been putting the 'Not Street Legal' in my wife's car.  Don't tell 
anyone.  ;)

-Brent

On 10/19/11 3:50 PM, Bryon Garvin wrote:
> I was re-reading some notes I took about the last time I inquired on a ZDDP
> additive and also using an oil with ZDDP already in it.  Jim said that the
> Lucas product he bought, if used as directed, would bring the ZDDP level to
> 5000 ppm.  But Jim you said also that you'd probably use the product about 2
> oz per oil change and leave it in there, as opposed to draining the system
> after 1000 miles like the bottle says.  I also noted that there is sometimes
> a warning that too much ZDDP is not a good thing either.  So, how do we know
> how much ZDDP to use?
>
> I opted for Valvoline VR1 at my last change which has ZDDP in it.  The only
> info I can find on it's ZDDP content is the MSDS which claims the ZINC
> ALKYLDITHIOPHOSPHATE level to be 1-1.5% of the quart.  I have a bottle of
> the Lucas product that I haven't opened yet.  I'd use the Lucas additive if
> the 2 oz at each change will give the proper ppm.  If it's unknown what
> using ~2.5q of VR1 contains with regard to ZDDP, maybe I should switch.
>
> Can anyone shed light ?
>
>   - Bryon, '71 Fastback
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