[928uk] High Mileage Nervousness - Cam Chains

[Paul via 928uk]

Nice one Marton

Fortunately that only shows that I was aware of the issue some time ago,
but didn't think my car would last so long that I'd have to be concerned
about it...

Paul


On 17 October 2015 at 22:32, marton hasenberg via 928uk <
928uk at lists.928.org.uk> wrote:

> Hi Paul
>
> Did a search and found this from 2009 - from someone named Paul - not sure
> it helps  :)
>
> `
>
> Oh dear God!
> For what it's worth I use Penrite HPR15, and this is my reasoning:
>
> There was an informed debate on the Landshark list sometime last year
> about Oil. This basically seems to have concluded:
>
>    - Flat face hydraulic tappets (used in the 928 but not more modern
>    cars) require levels of Zinc (ZDDP) that were present in oil until the mid
>    90s for protection
>    - Modern Cats are poisoned by ZDDP, thus newer oils have lower ZDDP,
>    older Cats such as those on the 928 are more robust
>    - Newer oils also have generally lower viscosity to enable them to
>    meet fuel efficiency requirements
>    - 928 bearing failures are associated with low viscosity oils and hot
>    environments
>
> Following this I have decided to stop using generic 10W-40 semi-synth, and
> switch to Penrite HPR15 (15W-60) which is approx £30 per 5ltrs.
>
> I hope others who were ignorant of the ZDDP issue will reseach this for
> themselves and reach their own conclusions.
>
>
> The chain sprockets on the cam shafts can lose teeth, this happens when
> the cam chains stretch. The standard advice is to replace cam chains if
> there has ever been piston valve contact, but I'm not sure whether there is
> a fixed replacement interval. I expect people tend to replace the chains
> when replacing the nylon tensioner pads.
>
> Paul
> 87 S4 Manual
>
>
> Mit freundlichen Grüssen/ with best wishes
>
> Marton Hasenberg
>
>
>
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> 928uk at lists.928.org.uk
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>
>
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