Doug Hillary

Hi,

This Oil Condition Report (Used Oil Analysis - UOA), the seventh, relates to the current engine oil in my car. It may be of interest to those who have followed the previous six reports over the past almost two years

The oil and filter were NOT changed at this point as ExxonMobil's Lab. report OK'd the oil for continued use. It will be changed at Porsche's prescribed maximum time limit

Mobil's Delvac 1 5w-40, a commercial HDEO (heavy duty engine oil) with both diesel/petrol ratings is used, this is the third UOA on this lubricant
This, the latest API rated "mixed fleet" diesel engine oil - CI-4/SL - also exceeds ACEA's A3 and B3 ( E3,4,5 & B4). It is suitable for high performance petrol engine vehicles and meets the car's viscosity needs and exceeds the quality requirements stated in the Owners Handbook

Details:

Car - MY89 - 928S4 Auto
Speedo - 133675 kms (83012 miles)
Oil - Mobil Delvac 1 - 5w-40 full synthetic - API rated as "CI-4/SL"
Oil/filter change date - 10/07/03 (OEM "MANN" filter used )
Distance since oil/filter changed - 16591 kms (10303 miles) Time since oil/filter changed - eight months ( approx )
Oil used since oil/filter change - nil (still at/near "FULL" mark )
Date of this sample - 5/13/04
Distance since last UOA - 8461 kms (5255 miles)
Time since last UOA - approx. three months
Use in this period (approx) - 5% town, 10% urban, 85% hiway
Avg speed in period - 80km/h (50 mph)
Fuel economy in period - 11.1ltr-100km (25.4 mpg Imp)(21.2 mpg US approx)
Ambient in this period - from 40c high to -5C low Humidity in this period - 98% highest

Oil Condition - "use" factors;

Note - UOA report figures:
Viscosity OK - 93 (excellent)
Water OK - 0.06%
Soot Index OK -0.00
TAN OK - 4.6 (excellent) - Start 1.00 & Max allowed 8.9

Lab. Report Summary

ExxonMobil's rating now - "Normal"
Status-Excellent for continued use
Last Report - "Normal"

Elemental (& wear metal) Analysis;

Detail of the Elemental columns are:
Col 1 = this UOA results (my comments are in brackets)
Col 2 = averages of all six UOA's
Col 3 = Oil Industry's "acceptable" max. wear rates (rounded) & not 928 specific

Iron 9 ( excellent ) [ 8 ] (( >100 ))
Aluminium 5 ( excellent ) [ 3 ] (( >30 ))
Chromium 1 ( excellent ) [ <1 ] (( >30 ))
Copper 5 ( excellent ) [ 5 ] (( >50 ))
Lead 8 ( excellent ) [ 8 ] (( >100 ))
Silicon 6 ( excellent ) [ 6 ] (( >30 ))
Sodium 8 ( excellent ) [ 8 ] (( >10 ))

Note:
The elemental wear rates are very low. All are around the previous averages and well below Industry acceptable figures. This indicates that rings, pistons, bores, cams, bearings and other major components are wearing at a very very low rate
This is another "technical analysis" of why the 928 engine is so durable in normal use when using the Porsche recommended (or better) lubricants that are changed at Porsche's recommended servicing intervals

Oil Condition Summary:

The lighter 5w-40 viscosity oil has now been used for 16591kms (10303 miles) - over about eight months. During this time the car was driven above 160km/h (100 mph) for extended periods in 33+C and below freezing temperatures

This very high quality oil has contributed to the overall lowering wear rate trends and has caused the wear trend averages to fall accordingly
The oil will be changed according to Porsche's time - maximum 12 months use - recommendation, as the maximum distance allowed will not be reached!

RENNLIST members now have a very good baseline of UOAs from which to measure their own car's wear rate trends from. This will also assist those persons who race our engines. A number of Labs. in NA do UOAs - but it is always better to use one that is well known

Regards

Lagavulin

Thanks for the report Doug, excellent as usual!

Jim bailey - 928 International

Thanks Doug ...over 10,000 miles and the oil is doing GREAT . Where "JIFF/econ/superLUBE" would already have done 3 oil changes it is in my mind nearly a crime for them to recomend such needless waste . Anyone who recommends such frequent oil changes obviously has more interest in the profit than anything else .

John Veninger

Thanks Doug

Jim_H

That's great stuff Doug.

I totally agree Jim.

Gretch

Doug, we now can get the Delvac 5w-40 in the states and I have ben "rat holeing" it by the gallon for the last 6 months. I have converted my two diesel tractors over to it and am thinkng about it for my shark. I currently use the mobil one 20w-50 in the shark and C4 as well and it holds up very well. I don't run either car in the winter so the oil only sees mild and warm weather operation. Mostly, my tractors thank you........

AO

This is great info Doug! Greatly Appreciated!

WWJBS? I agree. I have always felt that the quick lubes of the world were playing on the fears of the consumers. 3k MI what a bunch of unicorn Sh!+. I believe this falacy is further exacerbated by the fact that most vehicle mfg tend to recommend 5k mi or 7k intervals (IIRC my minivan is 5k). So let's put our collective thinking caps on and think this through.

Big OEMs want to minimize cost. Warranty claims are a BIG factor in their cost structures. One of the more expensive components is the engine. Further, the number one user-maintenance item is the oil. If the vehicle manufacturer says the oil needs to be changed at 5k mi intervals, they are basing this figure on a number that is far lower than the actual number so as to minimize warranty claims. (See the idea is that if they set the point at 5k they know that 2-3 standard deviations of the population will change it by, let's say, 8k miles.) So what do you really think the TRUE interval is? I'd say its likely that 10k - 12k mi intervals are probably more appropriate for any US/Japanese car that is under 20 years old. Anything older, I'd just go into top-up mode. Our P-cars are maybe a bit different, but I'm guessing Doug will reach 15k to 20kmi before a change is recommended.

I say you keep your money in your wallet and protect the environment.

(Flame suit is on for protection)

sharkmeister85

I haven't seen Doug's previous posts on this particular subject, though I am familiar with his great knowledge of lubricants on other posts. Should I assume that this is a recommendation that the Delvac is suitable for my '85 and should be put in at the next oil change or would that be getting too far ahead of the curve here?
Glenn

Doug Hillary

Hi,
thanks for the comments - and happy to share the data!

Andrew - when I commenced these UOAs all I intended to do was to confirm the Porsche Engineer's original recommendations for oils and oil change intervals (contained in the Owner's Handbook) were realistic and feasible. This has now been done.
And there is indeed a big margin of safety too!

Glenn - you may care to check out your needs here it may help you;

http://www.landsharkoz.com/techtips.htm

Check under "Lubricants for the 928"

Regards

slate blue

Great info and thanks for the effort.