ErnestSw

If anyone's interested, the Mobil 1 Delvac 5w40 can be ordered here:
http://shop.store.yahoo.com/avlube/fonfacsizcol.html

ew928

Thanks for the write-up, Doug.
Much appreciated dispelling of the 3000 mile/3 month myth.

Quote from Doug H.
-Many years ago Shell Rotella - a diesel oil - was THE factory fill at Porsche!
I think I have a shell sticker by the air cleaner on my 88 S4.
Something about filling with Shell lubricants and fluids.

So my question:
Should the yearly oil swapping be done in late fall,
or mid spring.
Late fall oil change would give the engine best freshest oil to
tackle the temperature extreme. (Cold goopy non-synth oil here in US).
Or spring oil change to empty out all the acids and water
accumulated during winter months.

Going for Amsoil Synth next week in my daily driver S4.
Would hate to try and crank over the big V8 with
goopy regular dino juice when it's waaay below freezing...

atb

Doug,

One thing that I'm curious about is how did the oil look?

Was it no longer opaque?

I realize that the color of the oil may have little to do with its condition, but if I wait more then 6 months for an oil change my oil comes out pretty dark, black almost. Is this what your oil looked like after a year, or was it still pretty clean?

Doug Hillary

Hi,
Normy - cream puff?. I have just completed a 2200km round trip in one of my light trucks. Average speed about 120km/h ( 75mph )

The S4 is my second 928 ( the first was a simple 1981 928 )and was purchased by me with about 100000kms ( 62k ) on it
I have not advocated extended oil drain intervals - just to simply do as Porsche recommended. Extending oil drains requires regular UOAs to determine the interval

With cars that consume a bit of oil the Porsche recommended oil change interval remains - you are simply topping up the oil's additive package and adding substance to the oil. At each top up!

Oils have improved measurably during the last 20 years believe me or look at their specs!

Changing modern synthetic ( and premium mineral ) oils at 3000k ( 5000kms ) intervals is simply a waste of money - but then each to his own!

ew928 - Porsche recommend oil changes are done in the spring if you do not reach the distance limit before. So do I

Adam - The oil was opaque and "normal" for a used oil

Oils should turn a darker colour if they are doing their job well but it depends too on the engine's breathing/combustion processes. The oil's discolouring is a product of its detergent action and the additive package makeup too. Beware the oil that does not get darker perhaps - cheaper oils with low detergency tend to look "clean" for longer

Soon I will be able to post an Oil Condition Report on the HD Fleet type diesel'petrol oil - Mobil Delvac 1 5w-40 - currently in my S4. It will have done about 6000kms

Remember I only set out to substantiate Porsche's recommended drain interval - nothing more

Regards

Doug Hillary

Hi,
This may be of interest - the oil's appearance CAN tell a story.
If you use a good quality blotter and place a drop of engine oil on it the oil's contaminant load may become visible

a ) if the drop spreads evenly without leaving a "black" ring the oil is in good shape and doing its job

b) if the oil spreads only after leaving a black ring or not at all, the ring is the contaminant load. The bigger the ring the bigger the load

This is a simple test that was once used extensively by most Oil Companies
when doing in-field evaluation of ( mainly ) diesel oils. It takes a little time to learn how to interpret it correctly

Experiment - Have a Go!

Regards

Doug Hillary

Hi,
This post is directed to Marc@DEVEK

Marc,
some months ago you chose to express your viewpoints on lubrication as "facts" and became somewhat "personal" in the flavour of your exchanges with me on this Board

Sadly, eight or so months later you have chosen not to answer the questions you left open by such comments now that the final Oil Condition Report from my car has been published here

I feel that I now have no option therefore other than to take up the challenge of seeking a reply from you to the issues of that time - those that prompted me to offer to do the Used Oil Analysis

Your comments ( or ones supported by you ) are prefaced by Marc@DEVEK.
My replies are prefaced by DH

Marc@DEVEK - ( 23/1/03...if you find a multi grade oil, say a 15-50, that does not end up over time reduced in viscosity to the lowest weight...let us know cause then we can also have perpetual motion machines at our disposal! )

DH - This flippant comment has been debunked by the progressive Oil Condition Reports. The oil was still within 2% of its original viscosity after 12 months and 8426 miles use
The acceptable used oil viscosity limits are near 30% thinner or thicker than new!
No "perpetual motion" machine offered, needed or at your disposal - just the facts

Marc@DEVEK - ( So, I am glad that you like running your engine for a year or two on multigrade oil and I hope you enjoy the benefits of running a 10-15 wt oil. Maybe after the oil has been in a street car for a year or two, you can put it in the race car and due to reduced grade, get a few more ponies due to lower pumping losses! Of course, you may have to rebuild the engine a few time per year...hmm...I think that I am on to something here )

DH - The oil from my engine was indeed suitable for further use and with its high HT/HS of 4.80 and high TBN could easily have seen further service in a race engine. Sadly Marc, no more horsepower though as the oil still has ( almost ) its original viscosity - contrary to your assertions.
By the way Ferrari uses the same XHVI base stock in F1 racing!

Marc@DEVEK - ( For me, I will continue to change oil in the 3-5000 mile interval and/or when the oil pressure per temp unit drops.)

DH - You can change your oil whenever you wish. Such a wasteful attitude however does nothing to conserve diminishing reserves or anything for our environment.
I am still pondering over what "...when the oil pressure per temp unit drops." really means. Feel free to enlighten us all - but with facts that can be substantiated!

Perhaps you may be using incorrect lubricants if you can pick up such decreases in oil pressure so easily and so early in an oil's life!

Marc@DEVEK - ( 24/1/03 Need less to say, I disagree that your methodology for determining oil interval changes has any validity...Doug, at least you are on the right path and understand the driving conditions of your vehicles, however, unless you tested the oil at new, and subsequently every 10K or so, you really have no idea how much wear has occurred. )

DH - You may well disagree with "my" methodology for determining oil change intervals. But, in doing so you are disagreeing with every Oil maker, all Vehicle and Equipment Makers, Lubrication specialists, many Fleet Owners/Managers worldwide, the API and the ACEA.

Best of luck if you think you know better than all of us!

Now for what it is worth, this Board has the knowledge of what wear actually occurred in my engine over twelve months and about 8.5k. They can note the "virgin" oil test ( VOA ) and the progressive four UOAs following it. They can all use the results as a "benchmark" for their own purposes if they wish. So can you if you are humble enough!

But then I have been doing this type of thing for nearly forty years - just a little practical experience backup I suppose! And, no surprises either

Marc@DEVEK - ( Read this and you might change your opinions...want more info on the "change more often can't hurt, can only help" lay mans position? )

DH - Refer to the Oil Condition Reports numbered 1 thru 4. And, remember our environment needs our individual support

Marc@DEVEK - ( 24/1/03 - From : Randall, ) - When in the market for a 928, I was told by all the pros that a bit of oil consumption in a GTS was normal and was due to the previously listed facts. I just wander how many GTS owners change their oil before 3-5K and how many change it at 15K?

Oil brands, it has been my experience that when the hype is striped away, there is only a few oil MFG. that are offering a truly superior product.

Moisture in motor oil is very common. Every time a hot engine is shut-down and left to cool it will suck in water laden air (humidity) from any open port (no matter the size). It has been my experience, motors that are run (a standing idle) just enough to warm-up than shut-down will have the most moisture. However an engine in a car that is driven (not a standing idle) for at least 45 min. or more, will burn off most accumulated moisture no matter how humid it is.

Comparing oil requirements/recommendations of a Gas engine to the same of a Diesel is an apple and orange argument.

1. Large diesel engines operate in a much lower RPM range for a longer period.
2. The Diesel fuel is used as a lubricant.
3. Most large diesel engines have removable side panels bolted to the side of the blocks so the entire interior of the block can be cleaned during a major oil change ( Cat D398 (V12) every 600 hours).
4. The properties, quality and additives in Diesel and Gas are very different and after combustion do different things to the oil.
5. When its time to rebuild that diesel, you can order new cylinders that press in with your new pistons for just a few more duckies. )

__________________
24/1/03 - Randall,
Good wisdom! )

DH - While not made by you, you agreed with the above comments by "Randall".
The content contained some meaningful comments and a number of serious and quite obvious errors and flaws
Items numbered 1 thru 6 were answered by me at the time and the issue of moisture? - well how could you agree? And the requirements of petrol/diesel oils..............!

A lack of knowledge betrayed perhaps?

Marc@DEVEK - ( 24/1/03 - I still have not seen any light yet...

Here are some FACTS:
1 Navistar 7.3 diesel recommended oil change interval - "normal duty 6000 miles or 6 months, sever duty 3000 miles"

2 Subaru recommended oil changes:1st oil change
at 3 months or 3,000 miles with oil and filter change a minimum of every 7,500 miles.
For most stop-and-go urban driving, dusty, snowy or extremely cold or hot driving ( maybe to Subaru this is severe duty? ) to change the oil and filter every 3,700 or 3 months.

3 Ford Motor Company recommends a 200 hour oil change interval for vehicles that are idled for long periods of time. In the example of a vehicle idling 24 hours a day and driving 50 miles, this would decrease the time between oil changes from 100 days to 8.3 days when compared to the 5,000 mile interval method.

Obviously, some of you folks know more about engines, use conditions, driving habits, internal conditions, oil types, etc. of individual engines then most manufacturers of a piston engine vehicle! Doug, you know your engine quite well...good for you, your engines and your company! However, no 928 owner that I know has their engine oil tested regularly! I did not hear you say you test your 928 engine oil?

Most manufacturers have a "use" clause, obviously, you folks completely disregard this FACT cause you know better.

Help us out here.....are you saying that an engine "use" does not affect oil change intervals, condition of oil, etc?

Are you saying it is better to abuse the hell out of an engine, not be aware of that abuse and change the oil once a year cause there is "folklore" around more frequent engine oil change intervals? Yea, "abuse" takes many forms, one is just driving the little ole 928 around town in 1 mile increments....

Are you saying that it is better to be sorry than safe? )

DH - Parts of this composition by you were disputed by me at the time.
It contained a number of errors, flaws and much supposition and primarily, its content was/is not factually substantive

Was it just a case of "don't let the FACTS stand in the way of a good story" ?

Your Item 1 - the Navistar engine. I have been a long time user of that engine family in varying applications and could relate many stories to you about its durability - even when "abused' by some users. I cannot recall one incident of an oil related failure

Your Item 2, I use a ‘02 Subaru Outback 2.5 in my business. It has done 62k trouble free miles with OC intervals at 9k+. It is on a synthetic diesel oil and it does not consume oil between changes
I live in the tropics and regularly see temperatures around 105F - it sees speeds near 100 mph quite often. On a recent trip we covered 620 miles in 9,75 hours virtually non stop!

Your Item 3 - Ford's 200 hour oil drains with "....engines that are idled for long periods of time". This equates to 10000 miles at an average speed of 50mph!
The rest of this issue I answered some months ago!

Well Marc, I still take exception to your assertions of "abuse" by me of equipment in use and inferring that this is "my line". How wrong you are!

You cannot substantiate such comments and never will in my case

And yes, "folklore" concerning oil change cycles does exist and is perhaps easily perpetuated for profit by some. And these are generally not backed up by the facts. Much oil is wasted - especially synthetics - trashed long before its "use by date" or its condition warranted it

In summary, a good and competent Engineer will do the research and publish the facts for all to see. No "story" to disguise or stand in the way of the facts
I have done that!
As, I may add, I have been doing from time to time for over forty years

Regards

Normy

Doug- I didn't mean to criticize, just to add....

8^) Thanx for the hard work!

N!

ErnestSw

Doug,
There are none so deaf as those who WILL not hear.

Doug Hillary

Hi,
Normy - I welcome constructive criticism anyway as it makes for a better end result for all of us. You did add... and in a constructive manner - thanks

ErnestSw - yes !!

Regards

Jim bailey - 928 International

Doug one of the problems of being "self taught" is that the teacher never knows any more than the student . That unfortunately may lead to the "student" thinking that they know everything ! Once you KNOW everything then there is nothing left to learn . Once again I thank you for taking the time , effort and spending the money just to prove that Porsche was correct that oil could be good for at least 15,000 miles or 12 months . The " urban myth " that oil MUST be changed every 3,000 miles and is somehow "good" for the car unfortunately is difficult to eliminate . I have found , there is little to be gained debating with fools ; they are not constrained by facts , information, reason or the truth ... generally responding with ridicule , sarcasim and loud voices to "prove their point" ......... (perhaps much as I may have done here ) . Lub it or lose it ! pay now or pay later , ........... so much B S

mark kibort

I wish someone would do this with Mobil 1 oil used in a racing evironment.
these results are exactly why porsche recomends mobil1 for its street cars. street driving doesnt push the oil passed its limits, even after a year of use!

lets see those graphs and datum for racing!@!!!

MK

Doug Hillary

Hi Mark,

Mobil1 - yes, well as Castrol once advertised "oils ain't oils"!

It is a pity that Marc@DEVEK did not fully answer my previous questions on the thread relating to bearing failures when racing

Really credible and meaningful data may eventually lead to a balanced solution here and hopefully a "suitable fix" that we all can share

The formulation of readily available engine oils, either synthetic or mineral, do not always enable them to perform in an unintended application - like racing!
M1 in the lower viscosities at least, is probably one of these along with many other oil brands/types/viscosities

The selection of a racing oil is a specialised process on its own and for instance the M1 or Castrol etc. formulation we can buy locally may be and usually is a long way from that used in a car displaying M1 or Castrol etc. signs and racing at Le Mans or elsewhere in a sponsored team. We all know that!

ExxonMobil are about to release a Racing formula version of M1 in the USA as I understand it

No oil will make up for an inherent engine design fault either. They are formulated to meet a specific and universally agreed design criteria, and generally this is for normal use as agreed by the engine and oil makers - and warranty binding
They can be and are especially formulated for a gearbox/transmission design shortfall - often on an individual manufacturer basis - and warranty binding

The real problem with oils under operational stress is their ability to maintain a suitably durable film strength at high temperatures, under high load - and especially at high revs! And as well their ability to maintain viscosity under a continuous shear cycle is critical. Their High Temperature/High Stress ( HT/HS ) ability is a specific design criteria and the European A3 Rating ( and B3 too, preferably ) is the one(s) we want to see on our oil containers
This viscosity rating is 3.5 cSt at 150C. Many readily available oils meet this including some with a low viscosity. Some significantly exceed it and these are the oils that should be considered for racing purposes - most are in the higher viscosity ranges.

Unless suitably "fortified", low viscosity oils are simply not suitable for sustained high oil temperatures and high loads

Castrol at one stage recommended synthetic grades of 0w30 or 10w-60 for 928s used in "Club Days" or "Racing". It is noted that the 0w-30 is no longer sold in this Country but the 10w-60 is still readily available. It is thought that their base structures are different too

It is probably a case of "the higher HT/HS viscosity the better" all else being equal when racing. Synthetic racing oils using Esters and perhaps other special additives may exceed this by a substantial margin. Some high grade diesel engine oils that are suitable for a 928 engine have a HT/HS rating beyond 3.5 cSt too
Along with the HT/HS rating the oil's flash point is significant too as it may have a bearing on oil consumption at high temperatures. Excessive fuel dilution exacerbates this issue too - a racing engine problem

We cannot readily purchase Redline or Amsoil oils in Australia so I am not familiar with them. For racing use these may well be suitable. For normal use some of them allegedly "meet" the API or ACEA Ratings but may not be "Approved". This difference may be significant for day to day use in a 928 and is probably less so when racing. The correct choice is most critical

European specialised oil producer MOTUL's 300V is a racing specific oil with a great reputation.
It is probably not suitable for day to day use and they do make many others that are.
I believe 300V is available in NA - it is certainly available here in Australia. This oil is made in various viscosities up to a 15w-60 ( note the Castrol viscosity mentioned earlier) which was developed for long distance racing where fuel dilution is a problem. This ester based product is good for turbocharged engines as they tend not to leave coking deposits

Some high quality synthetic diesel oils with a petrol engine rating ( CI/SL ) like Mobil's Delvac 1 5w-40 could be tried too as this oil has a HT/HS viscosity of 4.1 and tends to hold viscosity extremely well when under stress for long periods. This has been my experience with this oil which is now in my 928 ( along with many other very expensive engines I own )

If more "credible" data can be made available some research may suggest a preferred oils group based on brand/type/viscosity range for use in racing a 928.

No hype, "no religion" just the facts!

I hope this helps

Regards