Jim--I recommend reading the article (as laborious as it is to do so).
Looking down the list of 200 or so oils that he's tested, it seems to me
that the very latest formulations (in the last two or three years) do
significantly better than formulations I recall being well-favored by GMC
owners 6-8 years ago (or longer), when the ZDDP thing first popped up. I
wonder if your experience takes into account these latest
formulations--there may not have been time to know, just based on actual
engine wear (as opposed to his accelerated failure testing). There may be
some much better additive packages being used now.
Rick "his testing is more severe, but still similar to, high-lift
aggressive cams with flat tappets" Denney
> Roller cams and roller rockers have little, to no, need for high
> concentrations of zinc and phosphorus. Both of which are suspected of
> shortening the life of "catastrophic converters". Most all modern engines
> now use overhead cams with roller followers. So, API has been complying
> with stricter guidelines on the use of metals as a wear prevention
> additive.
> Where does that leave the flat tappet engines? On low lift, and shallow
> angle of attack cam lobe designs, not much of a problem. BUT, if you get
> more agressive with lift and steeper, more abrupt, cam lobes, that require
> stiffer spring tension, experience has shown higher wear rates with the new
> oils. As the tappet faces and camshaft lobes, and to some extent valve tips
> and rocker arm contact surfaces see accelerated wear, that metal goes into
> the lube oil, some of which is trapped by oil filters, some not. Just a
> factor of friction.
> Jim Hupy
> Salem, Or
> 78 GMC ROYALE 403
>
>
> > Thanks Jim K, Fred H, and Bob Dunahugh:
> > Soo - is it your opinion that ZDDP is a myth? If this author's testing
> is
> > on all newer cars - could he be wrong regards our 1970's GMC MH engines?
> > Mike/The Corvair a holic
> > Still using "Demo 400LE" in my Vairs and GMCMH's
> >
> > Sent from my iPhone
> >
> > > On Jul 28, 2017, at 11:55 AM, Jim Kanomata
> > >
> > > Fred,
> > > Thank you for posting that valuable information.
> > > As much as we all like to think, we understand, an article like his is
> > > worth reading and understanding.
> > > Lot of what he covered was on the ASE Certification test I took to
> pass,
> > > both the first time and the recertification.
> > >
> > >
> > > On Thu, Jul 27, 2017 at 4:02 PM, Fred Hudspeth
> > >
> > >>
> > >> The degreed mechanical engineer who wrote this article asserts that
> the
> > >> ZDDP
> > >> issue is a myth!
> > >>
> > >> https://540
ratblog.wordpress.com/2013/06/20/motor-oil-wear-
> > test-ranking/
> > >>
> > >> 'Consistent with Blackstone's opinion rendered circa 2010...
> > >>
> > >> Fred Hudspeth
> > >>
> > >> Fred Hudspeth
> > >> 1978 Royale (TZE 368V101335) - Tyler, TX
> > >> 1982 Airstream Excella (motorhome) - Cooper Landing, Alaska
> > >>
> > >> Message: 4
> > >> Date: Thu, 27 Jul 2017 16:56:40 +0000
> > >> From: Bob Dunahugh
> > >> To: "gmclist"
> > >> Subject: Re: [GMCnet] Wich oil is better? ( Blackstonr's view )
> > >> Message-ID:
> > >>
> > >> > >>
namprd14.prod.outlook.
> > >> com>
> > >>
> > >> Content-Type: text/plain; charset="iso-8859-1"
> > >>
> > >> Outstanding review. But we still have to deal with Zinc. And the
> diesel
> > >> formula's cover that. Bob Dunahugh
> > >>
> > >>
> > >>
> > >>
> > >> _______________________________________________
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> > >>
> > >
> > >
> > >
> > > --
> > > Jim Kanomata
> > > Applied/GMC, Newark,CA
> > > jimk
> > >
http://www.appliedgmc.com
> > > 1-800-752-7502
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--
'73 X-Glacier 230 "Jaws"
Northern Virginia
Offlist email: rick at rickdenney dot com