Hi All,

I've been avoiding all my friends and have fallen for Adrian's book...

I was pretty shocked that synthetic oil change interval is every 15K for our car. I guess i've been wasting my hard earned $$$ doing it 3000-5000 miles.

I was wondering what oil weights you guys use, according to Adrian's book its says;

Castrol Syntec 5W-50
Castrol GTX 5W-30, 10w-30, 15w-50 (Europe only)
Exxon Superflo Supreme 15w-40
Mobil 1 5w-30 or 10w-30
Sunoco 5w-40
Havoline Formula 3 Synthetic 5w-40

I currently use Mobil 1 Synthetic 15w-50 (red cap) which was not on Adrian's book.

I live in Palmdale, Calfornia (High Desert ranges from 18degF to 110degF) elevation 2500-3000 ft above sea level.

I've heard some cars actually run better with certain oil weights.

Is this true?
Thx GP

 

I've just got my car back from the Porsche dealer for maintenance and they now use Castrol RS 10W60.

Regards

 

Hi GP,

My car is scheduled for service at my local Porsche dealer in two weeks time. I will let you know which oil they use.

Take care

 

I use Castrol RS 10-60W as well but then my car is far from standard. I used to use Castrol Magnatech 10-40W semi-synth before then. As long as you change it every year I would think you are going to be fine.

 

M1 10W-30, what the owner's manual recommends. It is hard to go wrong with modern oils. You won't notice any difference, but 15W-50 will take a little more power to pump around. That will reduce fuel economy and the power available to drive other things. Less than 1 HP, so you should not notice.

 

Here is information on the Porsche approved oils in North America, as posted on the PCA web site:

Porsche's latest approved list of oils appeared in Technical Bulletin 1701, and they are all synthetic:

Castrol Syntec 5-50 (G)

Mobil Mobil1 0-40, 5-40 (GL) [Correction 5/2003: used to say 5-50, correct listing is 5-40]

Sunoco Synturo Gold 5-40 (GL)

Havoline Formula 3 Synthetic 5-40 (GL)

Valvoline high performance synthetic 5-30 (GL)

(GL) means it has good "light running properties" such as what we are discussing above with respect to cold winter performance. So the Castrol 5-50 is rated too high for this. In other words, no one is questioning the "50" part of their designation, but the "5" part is in question. We can assume from this that the 5-50 can be more safely thought of as a 10-50 or 15-50 for this discussion.

Likewise note that your Mobil1 15-50 is NOT approved by Porsche for this (year-round use).

Since the list above was printed, there is a newer list as of 5-23-03 (though not specifically for 993, there are separate lists now for Boxster, 996, Cayenne, GT3, etc) which lists dozens and dozens of brands and products. All are synthetic or synthetic blends. Unfortunately the list is for the European retail marketplace, not for North America, so the list is in need of some heavy translation to sync up with what we find in our stores and shops over here. Just try asking for Hunold Schmierstoff Eurolub Synt 5W-40 or Meguin Megol Super Leichtlauf 5W-40 at your local WalMart and you will see what I mean.

Joel Reiser - PCA WebSite - 7/11/2003

---------------------------

Note, for heavier duty, ie track, use, Mobil 1 15W-50 or other synthetic xW-50, or dino 20W-50 is often used.

 

Hi,
a translation of the minimum Porsche specification for engine oil you should aim for is as follows;
A Group 3 oil (synthetic or semi-synthetic),
Quality standard ACEA A3-96>/B3-96>,
Viscosity 0w or 5w-40 to 5w or 15w-50 (the minimum High Temperature/High Shear (HTHS) viscosity must be 3.5cSt, this HTHS vis, will NOT be met by a 5w-30 and most 10w-30 oils)
(a HTHS above 4.5cST such as in Castrol's RS 10w-60 (a Group 4/5 synthetic) will tend to sap power and raise the engine's operating temperature but may be preferred in racing with over fuelling)

Porsche "Approval" is quite important as it refers to the Company's anti-foaming protocol along with some others

The HTHS viscosity (a current test protocol) is critical too - it is a measured "shearing" at 150C and if it is too low (such as in 0w-20, 5w-30, and most 10w-30 multigrades) will likely cause premature wear in the valve train components and in journal bearings
The B3-96> quality standard (actually for diesels) is also critical as it requires the oil's formulation to handle deposit control in the ring belt and turbocharger bearing areas (amongst other things) and has long been a Porsche requirement

This link may also assist in understanding oils;

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

Check under "Lubricants for the 928"

Regards
Doug

 

Doug,
"he HTHS viscosity (a current test protocol) is critical too - it is a measured "shearing" at 150C and if it is too low (such as in 0w-20, 5w-30, and most 10w-30 multigrades) will likely cause premature wear in the valve train components and in journal bearings"

Is Mobil 1 10w-30 going to pass this test?
-Eric
90 C2
NER/PCA
(winter 10W-30 M1, instead of 15W-50, but now concerned)

 

I always used mobile 1 30wt. Last service they put in 50wt and I got my first oil leak...EVER! I don't think you need the 50wt unless you are tracking the car. I think, especially at cold start, its just too much pressure in the system. I'm switching back to 30wt on the next change.

...Plus if its Adrian's book...that's a strong indicator of what is "right".

 

Hi,
GP964 - check out the eight "Oil Condition" Reports via "search" on the 928 Forum. This gives a clinical appraisal of the durability of engine oils in Porsche engines when following their recommended service intervals

Eric - M1 10w-30 has a HTHS of around 3.17cSt which falls short of Porsche's minimum of 3.6cSt and while your engine will not quickly self destruct I would not use it in your application

A better all year round oil is M1 0w-40 (HTHS vis 3.6cSt & Porsche Approved).

Or you can use M1 SUV 5w-40 (the same as Delvac 1 5w-40) both of which have a HTHS vis of 4.1cSt and being "mixed fleet" lubricants exceed the Porsche standards by substantial margins. These two oils are ideal in turbocharged engines

As Bill pointed out earlier here and on another thread the "?w"-XX applies to the winter rating of the oil and its ability to meet established protocols set at various temperatures below -5C. The upper part of the viscosity range ?w-"XX" applies to what it is at 100C. The HTHS (shearing) viscosity is rated at 150C as mentioned earlier and is more indicative of how the oil handles the operating temperature at critical load carrying or wear surfaces

LA964RS - it is most unusual to get oil leaks caused by changing to an oil with a higher viscosity and from the same immediate "family". There may be another reason

Mobil 1 5w-50 or 15w-50 is porobably the most widely used oil in Porsche engines prior to 1992 build

Christer - Castrol's RS 10w-60 is 2.5 times more viscous at 5C than M1 0w-40 and is still 2.2 times thicker at 40C. It has a HTHS vis of 6.6cSt and almost twice as thick as Porsche's minimum. It may be OK for racing but is suspect for normal road use. It is only recommended by Castrol in Australia for "track days". Castrol's RS 5w-40 is a much better choice
I have used this wonderful Castrol oil in many more suitable applications with great success

Regards
Doug

 

Doug

The oil I use is recommended by the people that built my engine. The oil might be 2.5 times thicker at 40deg but my engine will not stay at that temperature for long. In fact I cannot imagine my car ever operating at that temperature for any lenngth of time. I am purely concerned about high temperature protection, and the car puts out quite a bitmore power than a standard car, and I have noticed that under hard driving the temps certainly go up faster if not that much higher than before. I guess this is obvious - more power more heat? It also revs to 7500rpm or so....actually maybe currently 7300....but capable of 7500.

As I said above, if I had a standard car then I would happily use x-40W oil...and semi synth as well. I guess I I am just going by what the engine builders suggest.

I should possibly stay out of these polls as my situation is quite different to the norm.

 

p.s. - what does 'suspect' for normal road use mean?

 

Hi Christer,
you should stay in this type of Forum of course and all perspectives are welcome

"Normal road use" is as Porsche designed the vehicle for - that's why we own them. Some people chose to track or race them - that is not "normal road use"!
My cars cover around 20k kms per annum a lot of time at speeds near 160km/h for hours on end and mostly in the tropics too where the ambient is 35C+ and in winter we spent hours in snow covered mountains sometimes at similar or higher speeds - this is my normal road use.

Castrol's recommendation of their RS 10w-60 for "track days" obviously applies in your case. Oils with an HTHS beyond 5cSt tend to cause journal bearing erosion and other adverse effects. These high HTHS viscosity oils do not always handle heat better and tend to run some engine components hotter. They may also cause excessive valve train component wear amongst other things

Regards
Doug

 

My owners manual (page 72 for a '91) has a table. The table identifies oil grades for synthetic and non-synthetic oils against an outside operating temperature. In it, it says that 10W-40, 15W-40, and 15W-50 are acceptible synthetic grades for temps that are mostly greater than 50 deg F. In fact for the grades I just mentioned, the synthetic table actually bisects the colder range that includes the "mostly lower than 50 def F". The ranges in the table are :

Mostly greater than 50 deg F/10 deg C
Mostly less than 50 deg F/10 deg C
Mostly lower than 14 deg F/-10 deg C

I've always been using 15W-50 Mobile 1. Has Porsche changed there mind on this oil now? Some of the oils they now appear to be recommending don't even appear in the table!

 

Hi Bill,
IMHO and as mentioned earlier, M1 15w-50 is an excellent and suitable engine oil for your car according to the prevailing ambient temperatures that range from -15C to 40C+. It has a pour point around -45C.

In Australia and in Europe a M1 5w-50 version is sold and as stated earlier:
"Mobil 1 5w-50 or 15w-50 is porobably the most widely used oil in Porsche engines prior to 1992 build"

Since your Owner Manual was printed Porsche has updated their recommendations a number of times with good reason. In this time (since '91) at least five API quality grades have become obsolete and three that are still current (SJ, SL and CF) will soon be superceded
In March 1996 the Euro manufacturer's "ACEA" quality ratings (A3-96/B3-96) were introduced and of course became their prime standards. These have since been updated a number of times

The synthetic oils that are available now are a quantum leap ahead of those around in 1991. Their technologies are much more advanced and so are the test protocols. These are constantly being upgraded as engine technology, metallurgy and chemical additives and new base oils are developed

If you are happy with M1 15w-50 stick with it - the "SuperSyn" version of Mobil 1 is a real world wide leader in lubrication technology!

Regards
Doug