You are correct, of course. I was thinking of roller cams when I wrote
'hydraulic' (shouldn't post so late at night, I
guess).
Thanks for setting that straight.
Bob
On 6/25/2011 9:53 PM, John Miller wrote:
>> By all accounts, a non-issue unless you're running a pushrod engine
>> with solid, 'flat' lifters. There are reports of premature cam
>> failures on this type of engine, but I haven't heard of any problems
>> with hydraulic lifter or OHC engines (which is pretty much all newer
>> engines).
>
> No, any 'flat-tappet' - that is, mechanical or hydraulic lash adjustment but
> non-roller lifter sliding on cam lobe -
> engine is at risk from reduced ZDDP levels.
>
> As are some OHC motors, typically those running stiffer-than-stock
> valvesprings with aftermarket cams on bucket or
> other sliding-type lifters.
>
> There's lots of good reasons to build your engines with roller-type valve
> actuation hardware where possible, and this
> is just another.
>
> IIRC API SJ was the last really 'good' oil, SL had half the ZDDP, SM was
> halved again from SL, and I now see an SN and
> I have no idea what it's got.
>
> John.
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--
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Bob Spidell San Jose, CA bspidell at comcast.net
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