Doug Hillary

Hi,
some time ago I agreed, after "spirited" posts here, to monitor the condition of the engine oil in my car. This was to confirm the oil change recommendations from Porsche namely - 20000kms or 12 months for "normal" use
This then is the second report, six months after the oil and filter were changed

Details:
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• <font size="2" face="Verdana,Tahoma,Helvetica">Car - MY89 928S4
  Speedo - 111831kms
  Oil - Shell Helix Ultra 15w-50 - full synthetic
  Oil/filter change date - 10/17/02
  Distance since - 8316kms
  Oil used - nil
  Date of this sample - 4/21/03
  Distance since last sample - 1719kms
  Use in period - 17% town,31% urban,52% hiway
  Avg speed in period - 66 km/h
  Fuel economy in period - 12.3ltr-100km
  Ambient in period - 34c high to 21c low
  Humidity in period - 98% highest</font></li>

<font size="2" face="Verdana,Tahoma,Helvetica">OIl Condition - "use" factors;
</font>

• <font size="2" face="Verdana,Tahoma,Helvetica">Note - last report figures shown thus new/old
  Viscosity - 98/94 OK
  Water - 0.01%/0.00% OK
  Soot Index - 0.00/0.01 OK
  TAN - 2.6/3.2 OK - the Max allowed is 8.9</font></li>

<font size="2" face="Verdana,Tahoma,Helvetica">Lab. Report Summary
</font>

• <font size="2" face="Verdana,Tahoma,Helvetica">ExxonMobil's rating - "O-Normal"
  Status-Excellent for continued use
  Last Report - "O-Normal"
  Estimate of distance to oil change - 25000kms
  Estimate of total oil life distance - 34000kms</font></li>

<font size="2" face="Verdana,Tahoma,Helvetica">Elemental Analysis;
</font>

• <font size="2" face="Verdana,Tahoma,Helvetica">Iron - 7/6
  Aluminium - 2/3
  Chromium - &lt;1/1
  Copper - 5/3
  Lead - 4/4
  Silicon - 11/22
  Sodium - 2/5</font></li>

<font size="2" face="Verdana,Tahoma,Helvetica">Note: None of the movements are significant. The silicon level fall is positive
The oil has survived 8316kms (5100lms) and six months very well. Porsche's recommendations look good
Regards

Nicole

Thanks for researching this, Doug!

This should silence the Jiffy Lube advocates...

kaamacat

Doug. Now thats a nice piece of work. (you can always get opinions from everone, myself included, but there is nothing like data data data).

Question. Are there any "thresholds" that get you into a warning or "critcal" area where the oil has been spent based on the #'s?

One final question. Do you know the running temp of the car during the test periods, overall.

Again. Cool (and appreciate) stuff.

Bob

Doug Hillary

Hi,
Nicole - thanks for the comments

Bob - yes "use condition" thresholds do exist and are;

Viscosity - 93 low to 139 high
Water - 0.05% approx
Soot - 3ppm approx
TAN - 8.9 - but depends on starting TBN

The TAN figure will vary according to oil brand, type and whether it is mineral or synthetic
The elemental components upper ;imits are unknown due to no data being available on the 928 from Porsche, Oil companies or other users. Sudden significant rises would be a worry. But certain manufacturer's engines do have specific levels - say Copper 120ppm, or Iron 100ppm etc.
The levels in my engine are very low

Yes, I have taken temperature readings and the averages follow;
Ambient - 26C M31-L23
Gauge - 85C M85-L87 Est
Thermo housing - 85C M88-L78
Top hose - 76C M88-L61
Bottom hose - 79C M90-L72
Valve covers - 88C M90-L85
Vee - 88C M90-L85
Oil cooler top line - 77C M88-L71
Oil cooler bottom line - 77C M90-L70
ATF line top - 63C M63-L52
AFT line bottom - 56C M54-L50

M is Maximum C
L is Lowest C

These measuremenst were taken with an infra red gun at the end of various runs from about 300kms to about 15kms

Note that the Shell oil is being tested in a ExxonMobil Lab.

Regards

Randy V

Wow, I really enjoy pure scientific method fact-finding, Doug. Impressive.

Did you tell us what the anticipated duration for this test sequence will be?

Doug Hillary

Hi Randy,
thanks for your comments

The oil will stay in until it is "no longer suitable" by analysis, or twelve months whichever is first. I have a sneaky feeling it will be twelve months unless a disaster takes over

If there is enough interest we can perhaps continue with the next twelve months period too after the oil is changed

These things can perhaps save owner's money and lead to better maintenance/servicing decisions

I'll take the next sample in mid July - in the middle of our Tropical winter

Regards

Nicole

The funny thing is that such tests have been done and published in Europe more than 10 years ago - I just don't have them in print anymore. Some European cars now come with 30,000km (about 19k miles) oil change intervals, and I would not expect them to fail prematurely - the manufacturers could not afford to deal with the complaints.

Europeans typically follow the manufacturers' recommendations (or go even longer), engine failures based on lubrication issues are rare - except maybe for too low of an oil level. In the two years I worked in an Autohaus, we did not have one single oil related engine failure (I would have known, as I wrote all the invoices).

Unfortunately consumer education here in the US is heavily based on advertising and clever PR work of the very companies trying to maximize their profits. Car magazines are so cheap, that they can only survive by catering to the advertisers - they are not going to tell us the truth either. Their testing is so shallow - they would probably not even find the truth and to avoid being sued, they'd follow the oil manufactureres... Most European magazines I've seen are much more thorough and less afraid to tell the truth.

I'm glad you are spending the time, effort, and money to straighten out this issue. You will save lots of people money and time that they can use for other, more important maintenance issues.

The 928 has one of the largest oil reservoirs of it's time, so the oil experiences even less stress than in other cars. Think about it: An oil change service on the 928 costs about $140 (with Mobil 1 oil and filter). You can do it every 15k miles, or spend five times as much ($700) to do it every 3,000 miles - wouldn't these $560 be better spent on a small service every 15k miles?

Maybe you should post this info on other Porsche related boards as well...

Normy

Doug-

Could you tell me who you've been using for this oil analysis?

Your car is an '89...which is a later 4-valve model. I'd be interested in doing the same analysis for my '85 S2, which is a 2-valve ROW car.

[I'm not sure how much difference there would be, and I'm pretty sure my engine is in good condition: I took the number 5 intake tube off today, just to examine the intake valve. I was astonished- it looked almost perfectly clean, with no soot or even any discoloration visible]

Oil analysis of this sort is routine in the aviation industry; programmed maintenance schedules depend on how much time an engine has accumulated, how much time has been spent at full power, and on things such as oil analysis. As you eloquently stated, it is the trend that is important...I'd love to do a yearly or twice-yearly oil analysis [I change my dino-juice at 3 month intervals, since my car sits in the garage most of the time] just to have a baseline.

OT: Trends are indeed important. I just got word from a friend today...who happens to be a pilot at Northwest Airlines. Pilots have to have yearly or twice-yearly medical exams, and when you turn 35, they make you take an electrocardiogram. I had my first about two years ago, and it seems that I am indeed alive [I was wondering for a while.... <img border="0" alt="[ouch]" title="" src="graemlins/c.gif" /> ]. No problems for me...but for him, despite the fact that he is in PERFECT health [a regular gym rat!]...he failed his EKG. This means:

1. Suspension of his medical.

2. Suspension of his employment with NWA.

3. The end of his $124,000/year income...!!

They do this check at 35 to come up with a "baseline", something that they compare your later results with. He had some sort of arythmia... or basically "bad timing" that the FAA won't accept. He has the option of going to several cardiologists and with testing...probably getting his medical back. But at least he found out that there is a problem A LONG TIME before it could be come critical to his own health..or the health of the 150 some-odd people sitting behind him some day...

I have twice yearly medical exams...I recommend ALL of you do the same. You'll save your own life eventually...

Normy!
'85 S2 5 Speed

Doug Hillary

Hi Normy,
most Oil Companies run Labs. to do such things.

I have worked with four Labs over many years and recently both Castrol and ( mostly ) ExxonMobil.
I started ThermKing refrigeration units on trucks and my truck engines off on synthetic lubricants many years ago and used this testing to determine drain intervals

I have worked with ExxonMobil & Detroit Diesel
on this issue for many millions of kms and the trend analysis works. It is the interpretation of the results that can be the problem

It only becomes really meaningful when you have lots of accurate reference data. Sadly none is readily available on the 928. You can use my data as reference points if you decide to do your own testing. Perhaps sometime on a Post in here the real meaning of the oil specs. can be discussed - as they relate to analysis and use

As Nicole said previously, we are fortunate with the 928 to have a well designed lubrication ( and cooling ) system with lots of reserve capacity

Your advice on Medicals is excellent and it is good to deal with a Doctor that can call your records up and explain the trends - great advice!

Regards