Doug Hillary

Hello,
This is the result of the ninth Used Oil Analysis (UOA) of the engine oil(s) in my ‘89 S4

The oil and filter were NOT changed at this sampling point, after 3464 miles (5587kms) and six month's use. Exxon-Mobil's Laboratory OK'd the oil for continued use and it will now be changed at Porsche's prescribed maximum limit of 12000 miles (20000kms) or 12 months - whichever is reached first

I use Mobil's Delvac 1 5w-40 Heavy Duty (HDEO) commercial diesel "mixed fleet" oil and it has the API's CH-4/SJ quality rating (now updated - but I am still using the older version). It far exceeds the ACEA's A3/B3-04 requirements. It has ACEA's E3, E4, E5 & B4 Certification for severe diesel engine standards of high turbo-charger boost pressures, deposit control, heavy piston and bearing loads, elevated heat and extended oil drain intervals. Being dual rated (diesel/petrol) it is most suitable for use in high performance petrol engines
Although NOT Porsche Approved it FAR exceeds Porsche's original quality recommendations for the 928 and their current Approval regime. It's viscosity is recommended in the 928 S4 Porsche Owner's Handbook. (In North America I believe that this oil is also sold as Mobil 1 SUV 5w-40)

Using higher viscosity oils than are absolutely necessary to meet the expected ambient range in your area should be avoided in any 928 engine

Details:

Car - MY89 - 928S4 Auto
Speedo - 88602 miles (142677 kms) now
Oil - Mobil's Delvac 1 5w-40 fully synthetic HDEO - API quality rated as "CH-4/SJ"
Oil & filter change date - 14/09/04 (OEM "MANN" filter used)
Distance since Oil & filter changed - 3464 miles (5587 kms)
Oil used since 14/09/04 - nil (still at "FULL" mark)
Date of this sample - 25/3/2005
Distance since last sample - 3464 miles (5587kms)
Use in this period - 9% town, 12% urban, 79% highway
Avg speed in period - 42 mph (68 km/h)
Fuel economy in period - 12.1 ltrs/100km
Ambient in this period - 42C high to 18C low Humidity in this period - 93% (highest)

Oil Condition - "use" factors;

Viscosity OK - 88 (excellent)
Water OK - 0.09%
Soot Index OK - 0.00
TAN OK - 2.6 (excellent) the Max allowed is 8.9

Lab. UOA Report Summary;

ExxonMobil's rating now "Normal"
Translated status "Excellent - suitable for continued use"
Last Report "Normal"

Elemental (& wear metal) Analysis;

Details of the following columns;

Col 1- this UOA results in ppm (my comments are in brackets)
Col 2 - [?] rounded average of all nine UOA results

Iron 6 (excellent) [8]
Aluminium 4 (excellent) [<4]
Chromium 1 (excellent) [<1]
Copper 2 (excellent) [4]
Lead 4 (excellent) [6]
Silicon 3 (excellent) [7]
Sodium 4 (excellent) [4]
Tin 4 (excellent) [4]

NOTE 1: General summary

The results are typical of the previous eight UOAs and therefore normal. All of this UOA's elemental wear metal readings are at or below the previous averages for this engine and well below Industry acceptable limits. One Techron Concentrate fuel treatment has occurred since the oil change last September but no evidence of this appears in this UOA

The series of nine (9) UOAs indicate that the rings, pistons, bores, cams, cam, rod and crank bearings, thrust washers and other major components are wearing at a very very low rate indeed

The testing to date justifies using the Porsche recommended (or better) oils and following their recommended servicing intervals despite what some so called Porsche "experts" may say in promoting shorter oil change intervals

NOTE 2: Engine oil performance observations (Shell Helix Ultra /Delvac 1)

It is interesting to note the following issues now that over 25000 miles (40000kms) have been spanned by the nine UOA's covering two different viscosity synthetic lubricants

A - Oil viscosity

The first four UOAs (one year - 8.5k miles, 13.6k kms) embraced using Shell Helix Ultra, a Group 3 synthetic 15w-50 top quality oil. No oil was consumed during this period

The last five UOAs (18 months - 15.9k miles, 25.6k kms) concerned Mobil's Delvac 1 5w-40, a Group 5 synthetic oil of a somewhat lighter viscosity. No oil has been consumed during the total test period

Both oil viscosities were originally recommended by Porsche for this car but 5w-40 is the current recommendation!

B - Fuel economy and speed
During the heavier viscosity oil (Shell Helix Ultra) test period the fuel economy was measured at 12.2ltrs/100kms and the average speed was 69 km/h

During the lighter oil's (Delvac 1) test period (to date) the fuel economy was consistently better. The car was definitely driven a little harder during the last year and a half as well.
This means at over 100mph for very long periods and at between 30-40C temperatures

C - Wear metals

The lighter viscosity oil has certainly produced a downward trend in engine wear rates. This is a sign that even while the car was probably driven harder in the last 20 months the oil offered greater wear protection generally. This may have been during the warmup phase. It is easy to rightly conclude that the engine was better off because of the change to Delvac 1 5w-40

It should be noted that wear metals will increase in volume (in ppm) as time goes by until drained with the oil - they are too small to be filtered out

NOTE 3: Current oil condition summary

The oil has performed very well indeed and for those persons using Delvac 1 5w-40 in their 928 you have plenty of reasons to feel confident that you "caught the right tram"! The oil's viscosity is at near new and its ability to combat deposits and acids remain very high indeed

The oil (it will be staying on Delvac 1) and filter (MANN) will be changed in September according to Porsche's maximum time recommendation but it is still likely that the maximum distance will be covered first!
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).
The Sodium "action" limit would be reached theoretically at around 90 000kms

b) the highest wear metal uptake is Lead. Using this factor, the oil would last theoretically up to 100 000kms before the "action" limit is reached

c) the MANN oil filter will last for at least two years or 50 000kms

I do not advocate going beyond 12 months without changing the engine oil and filter in a 928

I hope this is of value to some Rennlist people. There are now nine Used Oil Analysis results published here that can be "trended" and used to monitor engine wear rates and the condition of the oil

Regards
Doug H
'89 S4

Daniel Dudley

Where is Delvac 1 typically sold?

John Veninger

Doug,

Thanks again for the great information you are sharing

drnick

doug, how does delvac compare to mobil 1?

Doug Hillary

Hi,
John - thanks!

Nick,Daniel - I did not mean this to seem like a "sell job" for Delvac 1

"Delvac" is the Trade name ExxonMobil uses for its Commercial range of lubricants. It has been in use for decades. Commercial oils are sold at Truck Stops or direct from Distributors.
An equivalent to Delvac 1 5w-40 in NA is M1 SUV 5w-40 - its formulation is almost the same

Delvac 1 5w-40 is fully synthetic Group 5 lubricant having about 25% ester and lots of PAO in its base structure. Being a Commercial lubricant it is designed primarily for Heavy Diesel engines but meets the API quality "SL" for petrol engines. It is especially formulated for high compression pressures/temperatures, turbo/supercharger operation, soot management/deposit control, oxidation resistance, base viscosity retention and long drain capability after sustained high oil temperatures. I have used it in my Interstate Heavy Trucks (500hp & 42t GVM) for many years and millions of kms

It is difficult to compare this oil to M1 (except see above) but it is generally agreed by Tribologists as being the best oil of its type available anywhere at any price

Just for the record I do not work for an Oil Company

Regards

tammons

Just out of curiosity, how much does it cost.

Doug Hillary

Hi,
tammons - it is about the same price as M1 0w-40 I believe. Many 928 owners use it here in OZ and some people buy in bulk and share it

Regards

bwebb77

tammons, I just bought the 5w-40 to do a change in mine. It was about $6 at Wal-Mart. Believe it or not AutoZone and Advance Auto did not have it in stock.

Jim bailey - 928 International

Once again Doug has PROVEN that 12 months or 12,000 miles is no problem for a high quality oil. Changing oil more frequently is NOT being good to your car and definitely NOT good for your wallet ! The "Instjiffmin" lube industry has done a very good job of misinforming the American drivers to the point it very nearly constitutes FRAUD.

Gretch

I purchase it by the gallon and get it at the local NAPA store. I had to pester them for several months to carry it. I use it in my whole fleet. 2 diesel tractors, a truck and four autos. Even the Harley gets it. By the gallon, it is no more expensive than mobil 1. I ususlly "clean out" the NAPA store when I go in for anything else. My big tractor has a 3 gallon capacity and the little one takes 2 gallons. The P cars are no slouches themselves holding between 8 and 10 quarts each.

I made the conversion based on Doug's studies and reports. It has made my life easier too. I can keep an inventory of 10 or so gallons of the stuff on hand and use it in anything that takes crankcase oil. I even converted a couple of my neighbors to it for their tractors......The NAPA guy is happy to carry it now......

Thanks a bunch Doug!!!!!!!

Jim_H

Doug,

I always look forward to your posts. Thanks a ton for the info you share.
I am curious how much 2-3 tracks days a year would affect the oil? Should I change after every track day? I know there is no solid answer to this but I am curious for your opinion.

drnick

so mobil 1 is rubbish then. does anyone know what delvac is called in the UK?

mark kibort

I think its great info, but i suspected this with our cars in street use. i think where the oil factor really becomes an issue, is when you are racing it. be interesing to see what my oil looks like chemically after 3 race weekends at 260f.

Mk

Jim bailey - 928 International

Kibort your oil often has chunks in it like cam gear teeth ! Doug is the only person I know who can tell you if 260 degree temps and racing is going to harm the oil.

mark kibort

Hey, this weekend was all redline 6400rpm shifts in the SCCA race. Ill have to see if i have any more teeth! havent checked since the last oil change 2 races ago. none after road america though ! (one 7000rpm shift, ahh, misshift)

MK