Nick

If what you write is true, why in the world would Porsche recommend waiting until 15000 to change the oil? One would think that they know something about the car and the oil it uses.

hacker-pschorr

If anyone would like to talk to a real oil expert, PM Doug Hillary. He has performed extensive oil testing in both Porsche's and commercial diesel trucks. His current oil test on his 928 is over 5,000 miles with the test results showing the oil is well within the tolerances set by the oil manufacturer. His goal is 12,000 miles before changing. He is changing the filter somewhere in there.

Oil reports by Doug Hilary – very interesting read:

Report #1
Report #2
Report #3
Report #4
Report #5
Report #6
Report #7
Report #8
Report #9
Report #10

AeroGT3RedWing

No, I wouldn't because I don't have access to a CGT. But, having changed my own oil more times than I can count (its so hard to do you know) I can tell you from experience that its in much better condition at 5k than 7k (the highest I've ever gone and will ever go). Furthermore, oil temps were higher after prolonged useage.

Why would porsche reccommend 15k service intervals? Why would they sell the PCB on 996's that failed? Why would they have repeated RMS failures? Porsche is not perfect. BMW reccommended 15k service intervals on the E46 M3, and I've seen oil that went that long and it was filled with crap. Why did they do it? Because service was provided by BMWNA. Cost cutting.

Those tests you posted are on what car? Driven how? He said he drove 100MPH in cold temps. Big deal! Oil wears down most at high revvs and high temps, not in cold weather. Did he track the cars? Drive them hard? I could give my car to my mother and under her style of driving I am certain the oil would last past 10k. I am also certain CGT's see harder driving than that and that the conditions within the engine are much harsher.

Oil breaks down under high temperatures over time. I am sure under light city driving an oil change may not be due for 10k + miles, but under heavy and/or track driving, a 15k mile oil change is being stingy and quite frankly foolish. Oil filters will absolutely not last longer than 3-5k. But obviously you guys know a lot more as you seem like the bunch who work on your own cars all the time. I'm just an engineer who's rebuilt motors and stuff before. And no car company would ever try to cost-cut or play down maintenance costs :rolleyes

AeroGT3RedWing

Here's the exact kind of thing I have been seeing (in early stages) on cars driven hard with 3-5k+ oil change intervals.
http://theoildrop.server101.com/ubb/...=008933#000000
Car manufactureers are not always right.

Doug Hillary

Hello,
I do not want to hijack this thread but a number of comments do contain misinformation and are misleading:

Alex - you can confidently follow Porsche's first drain recommendation of 15k. Sometimes a Factory fill engine lubricant is actually formulated to assist in rapidly "settling the engine in" for a long component life
In the case of the BMW mentioned by the following poster here, as I recall, it was a production and quality control issue that caused the M3 engine problems and NOT the lubricant

AeroGT3RedWing;
Engine manufacturers are correct in their statements as to the oil to be used, viscosity for temperature requirements and oil change intervals. Sometimes production/application issues call for a Service Bulletin type change to oil type or viscosity and this is well documented. See above for the issues with the M3. Too much depends on product liability and the cost of rectification under Warranty to get it wrong!
Toyota, VW and MB recently had issues regarding engines but in each case it was not their recommendations that were incorrect - it was the Dealers and Owners not following them that was the prime issue!
And I have seen this many times - in both petrol and heavy diesel engines!

You say:
"No synthetic oil I know if will last 15k miles without breaking down. Synthetic oils, under normal driving can last to 10k miles, but filters should be changed at least every 4-5k"

This is totally incorrect. I have used synthetic engine oils for around thirty years and can confirm that when they are used as recommended they can have a life well beyond your stated 10k. I have used a 60k oil change intervals (average) in heavy high speed diesel engine for most of the last decade. Engine wear was virtually non existent on inspection teardown at 620k, and most parts were reusable (engine bearings/pistons/liners(still crosshatched).
Hundreds of Used Oil Analysis (UOA) reports showed that the synthetic oil was still within specifications at 90k. Soot contamination was the prime mover for the oil change and NOT the level of wear metals present in the lubricant
In petrol engines synthetics perform even better!

As for filters - the OEM filters used by Porsche are very good and can be left in for the stated distance. After cutting open many many filters I have never seen a filter totally clogged when following the makers recommendations and even then they will by pass anyway. Most engine wear is caused by contaminants below those captured by the full flow filters fitted to most engines in any case

Filtration issues are mostly caused by Owners/service Providers using substandard (non OEM) filters. These issues can range from filtration media collapse or poor sealing to canister burst or fracture

In our high performance petrol engines the Manufacturer's OCI can confidently be used when using a Porsche Approved and Listed engine lubricant!

You say:
"Go out and look at some oil. At 3k on light driving good luck, but at 7k it will be obvious it needs to be changed."

I have been involved in field testing lubricants since the 1950s and "looking" at the oil will not tell you its condition! That is of course unless a major component failure has occurred and the oil has visable metal contamination or etc.

I am very experienced at using the Tribologist's in-field standard "blotter" test for oils but the only safe and sure way is via a UOA done in a Lab.

If a modern oil's Additive package is doing its job the oil could well be darkened after a very few miles of use. Of course oil left within the lubrication system at oil drain assists in this initial disclouration!

You say:
"Furthermore, oil temps were higher after prolonged useage....."

How was this measured and was "prolonged useage" beyond the recommended OCI?

I have never accurately measured any increase in oil temperature related to recommended use! And I may add on testing at up to six (6) times the Manufacturer's recommended OCI!.

You say;
".....and I've seen oil that went that long and it was filled with crap."

Please explain what is meant! What was it, how was this measured and by whom??

You say:
"Those tests you posted are on what car? Driven how? He said he drove 100MPH in cold temps. Big deal! Oil wears down most at high revvs and high temps, not in cold weather. Did he track the cars? Drive them hard?"

A) The car - a MY928 S4
B) I live in Australia's Tropics and we experience many months of temperatures beyond 35C and many days over 40C
C) The average "core" oil temperature in a 928S4 is around 93C (In my heavy trucks the average oil temperature is 103C with an operational high around 112C - engine shutdown is programmed for 120C (mineral oil)). I have used an IR reader for many years
D) The car was not tracked. My comments in here are for cars that are used normally and NOT tracked!!
E) I cover around 50k per annum - driving is medium to hard! It is never "abusive" in style but thats my Engineering training I suppose. A bit like comparing Stirling Moss and Juan Fangio if you like!!

You say;
"Oil breaks down under high temperatures over time."

This statement is misleading. Oil deteriorates for a wide variety of reasons and one is by NOT reaching around 70-75C and not holding this or above for some time
Oil does "break down" at high temperatures and Porsche's testing regime calls for prolonged testing at both the ACEA's A3/B3 test point of 100C and at the High Temperature High Shear viscosity test point of 150C. Much "shearing" (I presume this is the "break down" you refer to) is of a temporary nature and the original viscosities are maintained over time. Porsche's Approved synthetic oils handle both low and very high temperatures with ease

Some oils become more viscous (they thicken) in use and this may be why the likes of Amsoil is not on Porsche's Approved oil List. With modern engine technologies an oil that thickens one level out of original viscosity is much more damaging than one that thins one level

The link you provide to the BMW engine is of course inconclusive!

Many Euro engine makers have used long OCIs for years and without any major issues. I have an intimate knowledge of MB and engine oil life here in OZ. Their oil monitoring system is averaging around 12k taken over some years - and with engine out to 400k.No major issues have occurred and their standard oil is M1 0w-40 - the same as Porsche recommends. On my last two new MB vehicles UOAs showed that the oil was capable of a much longer OCI than the ASSYST system indicated

It is always a matter of common sense of course. I have proven via UOAs that in normal use both Porsche's and MB's recommended OCIs can confidently be followed and with a very substantial safety margin too

I hope this aids understanding lubricants and their application - and puts some misinformation to bed!

Regards
Doug

Nick

When they said you know oil, that was an understatement! Thanks for the very useful information.

W8MM

Thanks, Doug, very much for taking the time to write up your experience.

Instrumented science beats old wives tales and naive anecdotal observations every time.

Well done.

Steve N.

What about dilution from gasoline?

hacker-pschorr

Stop pouring gasoline into your crankcase - or in the case of the CGT the oil tank


Thanks for jumping in Doug - your incredible knowledge deserves to be shared outside of the 928 forum once and a while.

themarsman

It is always nice when someone who knows what they are talking about responds with facts and not speculation.

Thanks Doug!!! You the man!

On another note I am still going to get my oil changed once a year when it is in for other stuff though. Cheap insurance.

Ray G

Doug,

Great info. Thanks.

What about synthetic oil just sitting in the parked car (or on the self for that matter). Does it "go bad" with time?

Also, I was under the impression that Mobil-1 synthetic was not 100% synthetic, and other oils would be better, such as Castrol TWS. Is there any truth there?

I suppose your answers may be depend on typical usage. In my case, the cars I care about most would be seeing a significant amount of track use, or high-revs.

Doug Hillary

Hi,
Steve - since the introduction of electronically managed fuel and ignition systems starting in 1968, fuel dilution is now no longer really an issue in vehicles in normal use. Significant engine management system faults can create excessive fuel dilution however but these are usually quickly apparent in other ways. As well, a fuel smell from the dipstick is but one (when a dipstick is fitted) along with an increase in oil level in extreme cases

Up to about 2.5% by volume (of the engine lubricant) is considered OK and engine Manufacturers no doubt factor in their worst case scenario when setting their OCI's and viscosity charts. Used Oil Analysis (UOA) is the most accurate method of quantifying fuel dilution, but the quick and easiest way is via a "blotter" test

In engines designed for "tracking" - especially for endurance type events - some engine Manufacturers recommend high viscosity synthetic engine lubricants such as 10w-60, 15w-60, 20w-60 and etc. Specialist racing oil makers such as FUCHS, Motul ((they recommend 300V 10w-40 for Porsche), Repsol and Castrol do acknowledge this fact and market such lubricants for those applications so that the viscosity remains above critical film "strength" levels over long periods. Most of these oils are Ester based and really are unsuitable for prolonged periods of "normal" use due to their (typically) lower acid control additives and etc.

However, this thread is about vehicles in their intended "normal" use and all of my comments allude to this

themarsman - yes, I will continue to change my oil at annual intervals too - or at 20kkms - whichever occurs first

Ray - it is generally accepted in Tribology circles that normal synthetic lubricant does not "go off". In fact Castrol are still retailing oil here that was blended in 1998! As well, five years after production is generally considered as the "use by" date
Exotic synthetic oils blended for special purposes may have a short life span depending on the chemicals content and perhaps the level of esters used in the formulation

The word "synthetic" has been used out of normal context now for some years - it was part of the ExxonMobil v Castrol case in NA

Briefly, there are six base oil "Groups". Group 1 (solvent processed) is the most basic and Group 6 which was recently approved is for exotic chemical lubricants (still being determined as I understand it)

Group 3 oils are those hydro-cracked or substantially modified hydrocarbon lubricants typically known as "Semi synthetic". These are not chemically engineered. This was the Group of oils challenged by Mobil.
Some modern Group 3 oils that are the subject of special hydro-cracking Technologies now rival Group 4 & 5 fully synthetic oils but at a lessor price. Some Castrol, Shell, Caltex and etc. semi-synthetics fall into this class and are excellent products with VW, BMW Opel and MB Long Life Approvals

Group 4 base oils are chemically engineered. A typical example are the Polyalphaolefins (PAOs) based products

Group 5 base oils are a building block (blending) group of Esters, Polyolesters and etc. These are not usually sold as a stand alone lubricant. They are used in Group 3 and 4 blending

Mobil 1 is a bargain priced fully synthetic oil that is typically a Group 4, some are a Group 4/5 blend . Mobil 1 0w-40 is a truly great product when used as/where approved - and surely is one of the best ever volume produced lubricants

Castrol are long time producers of synthetic lubricants (I assisted with the field testing of some of their ester and Group 3 products). Their most expensive synthetics are Group 4 and the lessor priced "synthetics" are Group 3.
My family used Castrol's "R" ester (castor bean) based oils in racing motorbikes for many years. I lived near and knew Bert Munro, the subject of the film "The worlds fastest Indian" - it is a great film! He was a great bloke too!

It is wise to ONLY use the oils approved by the engine Manufacturer. Porsche has an Approval List and all of the oils Listed there will perform at around the same level

Ray, I would commence a system of Used Oil Analysis to determine the condition and performance of the oils in your tracked cars. Blackstone and other such Labs. do this quite cheaply. It is an excellent confirmation that you are using a suitable lubricant and that it is performing as intended - or not!

In normal use no engine lubricant meeting the same engine Manufacturer's specification will perform substantially better than another regardless of the brand. This is despite the advertising "hype" and mysteries people like to weld into the lubricants issue

I must point out that I have no connection in any way with any Oil Company

Regards
Doug Hillary

Ray G

Doug, thanks for your expert reply. I think I will do a UOA on my track cars now.

MANUAL

Thank you AeroGT3RedWing, Hacker-Pschorr, and Doug Hillary. VOA's and UOA's seem to be very good methods of monitoring engine health.

Doug,

I asked a lab today about the benefits of used oil filter analysis (UFA) versus used engine oil analysis (UOA). The tech. told me the difference was the UFA is designed to test for particles greater than five microns, relative to a) an OEM Honda Civic 1.6 L engine filter which is not designed to filter particles smaller than approx. 30 microns and b) the human eye can usually perceive approx. 50 microns.

At this lab, a UFA, including photographs, costs between $95 and $195 depending on the size of the filter which is about three to four times the cost of a UOA. Unlike the UOA, the UFA is designed to detect things like carbon (prevalent in diesel engines?), varnish and gasket material (recent engine rebuild?).

At another lab, a UFA costs $15 - $25:
http://64.233.167.104/search?q=cache...s&ct=clnk&cd=7

I have read the CGT requires a valve adjustment at 30k miles.

1) Would the carbon reading on a UFA at 15k and 30k miles be able to indicate whether the valves need adjusting or not?

2) Do you conduct oil filter analyses on either your 928 or your fleet vehicles? Why or why not? What are the disadvantages of UFA?

3) Do you agree/disagree with the following opinion from the BITOG forums:

The oil does the lion's share of handling the bad stuff, oil filter is just insurance. The Air filter is the key.

4) Why are you not using Mobil 1 0W-40 instead of Mobil Delvac 1 5W-40 on your 928?

In your opinion, does the 5W-40's virgin Total Base #, mg KOH/g (TBN) of 12 and virgin HTHS Viscosity, mPaˇs @ 150ēC of ? outweigh the pour point, cSt @ 40ēC, and HTHS 3.6 advantages of 0W-40?

5) Do you agree with the following opinion from BITOG? If so, do you think Delvac 5W-40 would be a better oil for the CGT? Since Porsche has approved Delvac 5w-40 for all Porsche 4.6,8 cylinder engines from 1973 onwards, theoretically, it might be suitable for its 10 cylinder engine as well, correct?

http://www.landsharkoz.com/tt/tt_pao.htm


What this VOA doesn't show is that the baseline TBN for Delvac 1 is 12.0-12.5, vs 10.0 for the 0w-40 and 9.0 for the regular 5w-30/10w-30. Delvac 1 is also completely shear stable, which you can't say for the 0w-40 formulation.

Well, I've looked at about 100 oil analyses from the VW TDI engine and from various Mercedes diesels and I haven't seen a Delvac 1 sample thin out yet - unless there was significant fuel dilution. Shear stabiliy is also more of a primary design criteria in formulating HD diesel oils, so this makes perfect sense. By contrast,I've seen three analyses results from the 0w-40 and two of them thinned out a significant amount. Mobils own SAE papers also show this type of shearing behavior for the 0w-40.

Finally, the VI of Delvac 1 is significantly lower than the M1, 0w-40 - about 160 vs 185 - so that tells me they aren't using much if any VI modifier in Delvac 1. You'll note that Delvac 1 is a more expensive formulation, so they're certainly not cost limited as to basestock quality ....

Run both of these oils in an engine that shears the oil - like the V-6 Camry - and I think you'll see the difference right away ....

http://www.mobil.com/USA-English/Lub...il_1_0W-40.asp
http://www.exxonmobil.com/USA-Englis...lvac1_5W40.asp

5) What is your opinion of the following website by A.E. Haas? Do you disagree with him on any of his points? Why?

http://63.240.161.99/motoroil/index.html

Doug Hillary

Hi,
Manual - to hopefully answer your questions and/or provide some opinions will mean a long post, I hope "the others" don't get bored in the process!

UFA versus UOA (Note a VOA is Virgin Oil Analysis - the analysis of new oil)
Actually the Tech may be a little incorrect with their comments - as well, I have never had exposure to a "UFA"

A UOA will show the levels of wear metals and some other debris, and will quantify the condition of the oil. As well, I use (via the Castrol, Shell and Mobil Labs) the Particle Quantifying (PQ) Index to evaluate the content of ferrous metals present in the lubricant

Again one UOA is relatively meaningless in regard to engine wear. Trending the UOAs wear metal numbers over time/distance is really what it is all about! There is of course a relativity between them when evaluating the results

Using UOAs to rate one oil brand of similar specification against another is really quite fruitless unless truely modern techniques such as real time Radioactive Tracer Technology is used and measurements such as nanometres per hour taken

It is generally accepted that as engine technology has become more "precise" more demands have been placed on lubricants. An example is the use of lubricants to act as an hydraulic fluid in the actuation of valve gear timing and etc. In heavy high speed diesels for example this was first recognised a decade or two ago when "wiping" pressures were increased many-fold on camshafts. And again with diesels when then cleaned up visible exhaust emissions (USA engines) by dumping soot into the oil!

Soot is a major condemnation factor in diesel oil. About 3% is considered a maximum by most engine makers but some synthetic diesel engine oils can extend beyond that. I use 3.5% which is Mobil's limit with Delvac 1 and I have occasionally gone out to 4.5% without any dire consequences. See under 2) below, probably the most efficient way of removing soot from oil is by using a centrifuge

Most FF oil filters - and especially the Porsche OEM's products - are reasonably efficient in removing debris down to about 15microns (depending on absolute/nominal value status)

The HTHS viscosity (refer earlier Posts) suddenly had real meaning as engine operating temperatures (and oil temperatures) rose considerably. It was realised that considerable wear occurred at micron levels below what a full flow oil filter could remove

In answering your questions;

1 - No. A UOA (with a PQ Index reading) at these points would assist in determining if wear rates are reasonable and consistent for your engine

2 - No - not on the 928 or with my Detroit engines. See preamble above. It all comes down to a cost/benefit analysis in my books.
I fitted MANN-Hummel centrifuge cleaners to my heavy truck (Class 8) engines which are Detroit 60 Series @ 500hp. We initially carried out a particle count of the debris in the centrifuge and monitored the FF filter's (Donaldson Synteq ELF) soot uptake. Over many 100k's kms we found that the FF filters were completely clean at 100kkms. Finally I replaced these with 30micron cleanable stainless steel screens. The centrifuge has proven to be so efficient that we no longer need to adjust valve/injector settlings at 200kkms. Adjustments became only an "as needed" item and went out to 800kkms+ .
This was only possible by using a centrifuge - the oil used was/is Delvac 1 5w-40
I have used Delvac 1 5w-40 for most of the last decade!

I trend Fe and the PQ Index of course along with the other wear metals in monitoring this

3 - Oil = Yes. To qualify the yes. The oil is a carrier of debris and those particles above around 15microns usually get left at the oil pump uptake and/or with the FF oil filter. The other particles remain in the oil until it is changed. There is only so much an engine's oil can do and the engine Manufacturer knows the facts and uses this data to set oil type, filter capacity and OCIs for general use
Those of us with early VW (and some Porsche) air-cooled engine experience where only an oil pump screen was used (no FF filter) will have been exposed to engines that lasted very well indeed. The screens only needed cleaning along with regular oil changes

3 - Air filter = Yes. Much wear is caused by unfiltered intake debris. I have watched 2 cycle diesel engines destruct rings and liners in under two hours or less when intake air filtration has been compromised. UOAs when done regularly will provide good data on the possible level of silicate being ingested (not to be confused with leaching from sealants etc.)
Good, tight, and suitably placed air intake tracts with suitable filtration is a must!

4 - Mobil 1 0w-40 versus Delvac 1 5w-40 in a 928's engine.
I like the "comfort" of the higher HTHS viscosity of Delvac 1 5w-40 in the 928 engine but many people use M1 0w-40 in their 928s with great results

a) I like the high TBN of the diesel oil in a low use engine and for annual oil or extended changes
b) I prefer the higher HTHS in a 928 (see above)
c) Both oils have great cold flow characteristics. I live in the Tropics, if I lived where the temperature was regularly below -15C I would use M1 0w-40. I use it in my Benz engines
As a matter of interest the SAE40 oil spends a lot of its time at a SAE50 grade rating in a 928 as the oil's temperature is usually around 89-93C in these engines

In engines designed for an oil having a HTHS viscosity of around 3.6cSt, M1 0w-40 is a great product. That is why Porsche, AMG and Benz etc. use it as factory fill

5 - The link you provide is to the Landsharkoz (928) site in Australia showing Porsche's Approved Oil List. It is relevant and Delvac 1 is not on it - however I suspect that one M1 5w-40 variant has a similar formulation

Do I agree with the BITOG poster's opinion? Well, I have great difficulty with the random assessments by some people on BITOG that M1 0w-40 is not shear stable! Some BITOG posters use various methods to decry this product because of this - have they more expertise than the engine Manufacturer that recommends it? I think not!!

Oils have a grade range (SAE at 40C and 100C) and in the case of SAE40 at 100C this is between 12.5 and 16.3cSt, the SAE30 grade range at 100C is between 9.3 and 12.5cSt
M1 0w-40 is rated at 14.3cSt at the mid point and in some applications it appears to shear to a become high SAE30 grade in the short term but yet restore itself to a low SAE40 nearing its oil change point. This matters little in the real world and does NOT cause extra wear!! See also under 6) A E. Haas, later
Some other oils however (for example some Amsoil products) tend to simply get thicker with use. In engines where the oil has a critical hydraulic function this is most undesirable.
I prefer to possibly lose a grade in use with an SAE40 lubricant rather than gain one!

In detailed UOA comparisons on early 911 engines, wear metal levels were found to be very similar when using mono-grade SAE30 oil, 5w-40 oils and M1 0w-40. Some engines showed lower wear metal rates on Mineral oils too!

As to the VI levels well these are hard to evaluate when not knowing the full structure of the base oil and the additive package used. Delvac 1 5w-40 had/has a significant ester component and in some applications this can be beneficial

Now, as to would I use Delvac 1 5w-40 in a CGT instead of M1 0w-40? - the answer is NO!
I don't use it in my new Benz Kompressor either - I use M1 0w-40 and oil temperatures reach near 140C at certain points in that engine
M1 0w-40 is a great product (there are of course some other excellent and Porsche Approved 0w-40 oils) which has a fabulous track record going back for nearly a decade

M1 0w-40 can cause some engines to be noisy at cold startup - this can be discounted!

Alway use the lubricant the engine Manufacturer recommends, Approves, and Lists!

6 - A.E.Haas
Mr Haas has some interesting theories. He is a "thinnest oil possible advocate" and has backed up his theories by testing in his own vehicles. He is also a short run and one could argue, not your average user

Thin oils are not new and in MY1941 the most common oils recommended for use in USA built cars were SAE20, SAE20W (up to 90F) and then SAE30. The original forerunner of "thicker" oils was the Duckhams 20w-50 multi-grade introduced in 1958-9 for the BMC Mini with the shared oil integrated gearbox. 10w-30 multigrade oils were introduced in the late 1940s early 1950s and are still popular

Euro manufacturers certainly tried thinner oils in the 1970s with some disastrous results but a move to less viscous lubricants is now underway again in Europe

We have moved on since the 1940s and thinner Mineral oils such as 0w-20 and 0w-30 are performing very well when used as when and as specified in some modern engines

I believe that the engine Manufacturer knows best when recommending lubricants and considering the high levels of sophisticated prototype testing and Oil Company co-operation they certainly should!

In other than a "general use" sense such as racing etc it will always be best to seek advice from the Oil Company's Engineers along with the engine Manufacturer's advice

Regards
Doug Hillary