Doug Hillary

Hi,
In response to comments from "Marc@DEVEK" I will commence a programme forthwith to sample the engine oil in my car a MY89 928S4
ExxonMobil have agreed to sample my oil as follows;

1 - new Shell Ultra Synthetic 15w-50 ( SJ/CF-A3 Porsche approved )oil sampled as baseline

2 - current oil in crankcase ( same batch Shell Ultra Synthetic 15w-50 ) will be sampled within the next month @ 7 000-8 000 kms of use
To enable accellerated results I decided to remain with my present Shell oil rather than move to Mobil 1 5w-50 or Mobil Delvac 1 5w-40

3 - samples will then be taken every three months - use factors noted in %, and top ups noted as is normal

4 - oil will be changed @ 20 000 kms ( maximum Porsche recommended ) or as the samples determine - whichever is first

5 - results will be posted here if anybody is interested

Note 1: Analysis will cover contamination, wear metals and viscosity - a "normal" analysis

Note 2: As we do NOT have a wear metal "history" on this engine the most meaningful parts will probably be related to contamination and viscosity

Note 3 : This engine has been well serviced from new and the speedo reads 109000 kms at present
Please comment

Regards

WallyP

It will be great to have a baseline.

I expect that you will find a bit more silicon than expected in the higher-mileage samples. Two reasons - the cylinder walls are high-silicon aluminum, and it doesn't take much of an intake leak to pull in small but measureable amounts of dust (silica).

Fastest928

Great Doug, I have performed the same for two engines from build to failure due to cam weldment birnelling. The primary damage was due to scraping of the cylinder walls by hardface (carried in the oil which get splashed onto the cylinder walls in large quantities,,,) which resulted in very high Si and Al content in the oil. This also increased leakdown considerably to the engine ... had over 10% in one cylinder!

It would also be worth performing a leakdown test using a differential tester. It will help determine how much, if any, wear has occured, see your note 2, and the current status of your engine. A few dyno pulls on a dynoJet (see dynojet.com) would also be useful

Regards,
Marc@DEVEK

Doug Hillary

Hi Wally,
thanks for you comments - noted, respected and confirmed - thanks

Hi marc,
I can't do much else as I live in "the bush" - 1200 kms North from Brisbane
With my other engines we have a long "history" of all sampled "elements" built up over time/distance up by the engine maker(s), oil companies and users. It then becomes easy to do a trend analysis - not so here
Your comments are noted and respected

Regards

T_MaX

Doug, grand idea! Can't wait to see the results.

Marc, where could one send an oil sample to here in the US?