Doug Hillary

Hello,
this is a Used Oil Analysis (UOA) of the engine oil in my ‘89 S4
It is No 11 and it will help enable others to compare their own UOAs for trending purposes

The oil and filter were changed near this sampling point after 3131 miles (5042kms) over eleven months. Exxon-Mobil's Laboratory OK'd the oil for continued use

I use Mobil's Delvac 1 5w-40 Heavy Duty (HDEO) commercial diesel "mixed fleet" oil

Details:
Car - MY89 - 928S4 Auto
Speedo - 93280 miles (150210kms) now
Oil - Mobil's Delvac 1 5w-40 fully synthetic HDEO - API rated as "CH-4/SJ"
Oil & filter change date - 16/09/05 (OEM "MANN" filter used)
Distance since Oil & filter changed - 5016 miles (8078 kms)
Oil used since 16/09/05 - nil (still at "FULL" mark)
Date of this sample -11/08/2006
Distance since last sample - 3131 miles (5042kms)
Use in this period - 8% town, 22% urban, 70% highway
Avg speed in period - 38 mph (61 km/h with a highest speed of 220km/h)
Fuel economy in period - 12.1 ltrs/100km
Ambient in this period - +42C high to 0C low
Humidity in this period - 98% (highest)

Oil Condition;

Viscosity OK - 84 (excellent) [88]< Average of Del 1 at OC (Virgin oil is 92)
Water content OK - 0.00% (0.06%)< Average of Del 1 at OC
Sodium content OK - 4 [5]< Average of Del 1 at OC
TAN OK - 2.7 (excellent - lowest is best, max allowed is 9)

Lab. UOA Report Summary;

ExxonMobil's rating now "Normal"
Translated status "Suitable for continued use"
Last Report "Normal"

Elemental (& wear metal) Analysis (in parts per million - "ppm");
Details of the following columns;
Column 1- current UOA result (my comments follow in brackets)
Column 2 - [?] rounded average of all UOA results at oil change

Iron 9 (excellent) [11]
Aluminium 4 (excellent) [5]
Chromium 1 (excellent) [1]
Copper 1 (excellent) [4]
Lead 3 (excellent) [6]
Silicon 5 (excellent) [5]
Sodium 4 (excellent) [5]
Tin <1? (excellent) [NA]

SPECIAL NOTE: The averaged figures are a good baseline for any 928 owner to use and apply to a non tracked road use vehicle!

NOTE 1: General summary

This UOA result is typical of all of the previous UOAs. Although iron is a little higher, the other elemental wear metal readings are at or below the previous averages for this engine and well below acceptable Industry limits

The full series of UOAs (taken at various distances) indicate that the rings, pistons, bores, cams, cam, rod and crank bearings, crankshaft thrust washers and other major components are wearing at a very low rate indeed

The oil testing done to date justifies using Porsche Approved and Listed (or better) oils at the Listed viscosity. It confirms that following their recommended servicing intervals is cost effective

NOTE 2: Oil performance observations (Delvac 1 5w-40)

A - Oil viscosity
A 5w-40 viscosity (the current recommendation) oil seems ideal for year round use in a 928!
Delvac 1 5w-40 has retained its viscosity very well indeed

B - Wear metals
Porsche's recommended 5w-40 viscosity oil has maintained the lower trend in engine wear rates
It should be noted that wear metals will increase in volume (in ppm) as time goes by until eventually drained with the oil - they are simply too small to be filtered out. The averages shown above are only from those samples taken at the oil change point for this very reason

NOTE 3: Current oil condition summary

Delvac 1 5w-40 has again performed very well and using in a 928 gives plenty of reasons to feel confident that we "caught the right tram"! The oil still has near new viscosity and its ability to combat deposits and acids remain very high indeed

The oil and filter (MANN) were changed shortly after the sample was taken

It is worth noting that by tracking both the oil's condition and the rate of wear metal(s) uptake the following data emerges;

a) the premium synthetic oil will last for at least two (2) years and probably three (3).
b) The Sodium "action" limit would be reached theoretically at around 90k kms
c) wear metal uptake rates indicate that the oil would theoretically last up to around 80k kms before any "action" limit is reached
d) the MANN oil filter will easily last for at least two years or 50k kms
I do not advocate going beyond 12 months in any 928 without changing the engine oil/filter

I hope this is of value to those RENNLIST people who want to maintain a condition history and "keep an eye" on thrust bearing and other wear/failure points in the 928 family of engines

Bill Ball

Doug:

You need to work less and drive your S4 more.

Doug Hillary

Hi Bill,
the CLK made me do it - don't tell anybody!

ErnestSw

Thanks again Doug.

RDS928S

Doug,

thanks for the great info.
What is your opinion on the new Mobil tri-synthetic 0-40 ?
That is what I am running in my 86S daily driver with 68k on the clock.

Regards
Rich

ROG100

Doug,
I have read all your reports and information.
Just re-read most everything to try and decide which oil to use in my cars.

Straightforward question : -

In the US I/We cannot buy Mobil 1 15W - 50 any more - why I do not know.
What should I use that is readily available? Preferably Mobil 1.

I live in Dallas, Texas.

AO

What? I swear i just saw it the other day in gallon jugs. However, it is marketed under their "Diesel" truck formulation. And as I understand it, Mobil 1 is Mobil 1. The Diesel Truck thing is just a marketing gimmick. Am I wrong?

ROG100

Andrew,
Maybe I should have said not in Texas.
WallMart are not selling it anymore - why I don't know.
I still have a few quarts of 15W-50 left.
With my fleet that does not cover much.
I am trying to decide on a readily available alternative as opposed to having to ship the stuff in or drive 200 miles to a special dealer to buy it.
Roger

AO

I see. So what you're telling me is that Wal-Mart is the only retailer of motor oil in Texas. Got it!

I know it's a crazy idea Roger, but have you tried other retailers? Venture outside your comfort zone. There's a whole 'nother world out there besides Wal-Mart.

ROG100

Like who?
I find the NAPA - AutoZone - OReilly place much more expensive than WallMart.
I don't think that the decision to stop 15W - 50 is a WallMart only decision.
I may be wrong. I think Mobil has stopped supplying it.
Hey I like my comfort factor.

AO

Actually, I think it was AutoZone where I saw it last. So let's say that's it $16/gal at your favortie Wal-Mart. But, *gasp* it's no longer availble through them. However, it is available at AZ for $20/gal. That's roughly $8 more per car/year. Assuming (BIG assumption) all 9 of your cars are running, that's still less than $100/year.

I know you would not miss a $100 bill over the course of a year, so it's not really an economic issue we're facing. It's an issue of change. Change can be a difficult thing to accept. But change is good. Without change, our beloved 928's would not be so beloved - as they would not be as rare or special to us.

All joking aside, have you ever considered buying it by the 50 gal drum? Probably cheaper in the long run.

ROG100

Andrew,
I think you are missing my point - and I am taking your comments with the humour they were written with.

Mobil 1 15W-50 is no longer available in my immediate area what else can I use?
Wether this availability issue is short term or long term I don't know.
Roger

fabric

It's now an "extended performance" oil:

http://www.mobil1.com/USA-English/Mo...ce_15W-50.aspx

I picked some up at PepBoys, it was the last 8 quarts they had. This change to it being referred to as extended performance happened fairly recently, so it may just be a blip in stocking. Not sure how often you're at walmart - I try to avoid it because the place just weirds me out - but might just pick up the phone and talk to a store manager, see what's up.

ROG100

Chris,
Already spoke to the store manager and confirmed no longer available.
Tried lots of places and its in very short supply or not at all.
Tried FL,NM,AL (Monday),MS(Wednesday), LA as well.
It changed to Extended Performance about a year ago - been using that until now.

Back to my point - what do I use?????

sharkmeister85

Why not the Delvac Doug reports on?
Glenn