Fogey1

mark kibort wrote: 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.

Good question Mark. Is this you volunteering to get a baseline analysis and then follow-ups through the season? Thank you. More data is a good thing.

mark kibort

sure, ive saved my last oil filter and certainly can provide an oil sample on the next change.

be curious on how good the oil still is.

Mk

Doug Hillary

Hi,
James - I would be very confident that the oil will survive lots more than one track day. The oil changes in my trucks are done at 100kkms (62k miles) intervals after operating in severe conditions - much of the time at 80-100% power. The average oil temp in this application is 103C (220f) and it often reaches 113C (240f). These engines have a ECU programmed power "ramp down" at 121C (255f) oil temp with mineral oil.
In this harsh application and operating circumstance I have never seen a viscosity loss of more than 3% (15% is permissible) and never any gain (40% is permissible) at all with Delvac 1 5w-40

I would take a Used Oil Analysis after each track day if it was my car (I think Mark K should too!) but I think the oil will last very well indeed in your application - one year or 20k kms
I think Ernest has "tracked" his car with Delvac 1 in and I know that others have too - it is much more robust than M1 0w-40 the Porsche factory's fill

Nick - well M1 is not exactly rubbish (or rubbished). The SuperSyn version is the most enduring and cost effective synthetic engine oil made anywhere - really great value for money and cost effective. Delvac 1 5w-40 is a sort of "super" version of M1 but has an entirely different base oil and formulation. It is sold as Delvac 1 SHC 5w-40 in Europe I believe

Mark - what oil temps do you see consistantly in your car? I am very interested!
Group 4 or 5 synthetic oils (including Amsoil, M1 and Delvac 1) of the correct viscosity (5w-40 and above) and with a HTHS viscosity of at least 4cSt will take sustained temperatures up to 130C (270f) without too much if any permanent shear (loss of viscosity).
Delvac 1 will resist oxidation better than most all others at these temperatures and is less volatile
Many of these oils will easily run in the 110-125C (220-255f) range for long periods without serious oxidation too
Mark please do a UOA after your track events and publish it here we could all benefit from it

Mineral or Group 3 synthetic or semi-synthetic oils are not as durable at very high temperatures
and IMHO any oil with a Xw-30 viscosity should not be used in a 928

Regards
Doug

jserio

Hey Doug, I have a question. If the car should happen to overheat ( gauge reading ). Using M1 how long do you have do you think until the heads warp or something else catastraphic? Does the oil type play a factor here?

Doug Hillary

Hi,
Joe - that is a very complex question - one with many possible answers
However, one clear answer is possible - if you have two similarly specced oils one mineral the other a synthetic, the synthetic will definitely provide a safety barrier as heat rapidly builds up. This will be measured in degrees C/f rather than in time but perhaps an additional 20-25C or so is near correct. Of course this is at wear surfaces - coolant caused damage is another thing of course
How long ? perhaps it may be an additional 30 seconds or so as many other factors intrude

An example;
The power ramp down/shutdown feature inbuilt in most mdern heavy diesel engines using a mineral oil is about 30 seconds and it typically works like this;
Normal oil temperature (OT) = 110C
a) a warning at 115C OT (usually a bright yellow dash light but sometimes audible)
b) power ramp down commences at 118C OT (power firstly reduced to 70% then additional warning (red light/auduble) and then power reduced to 40%)
c) engine shutdown occurs 30 seconds after b) above and/or at 120C OT

Some ECUs do allow an override (@ 40% power) with 30 second intervals preceding a final shutdown - to enable safe parking etc

If the ECU was recalibrated after trials using a similarly specced synthetic oil then the figures at a,b,c,) above would most likely be 120C,125C and 130C all else being equal!

As an another example I had a rear diff wheel seal fail in a loaded (42500kg) heavy truck at night and I elected to tell the driver to carry on the last 400miles of his journey at a reduced speed monitoring the oil "mess" at the wheel. After the trip the oil level was down to about 1/3rd. It only required one new wheel bearing(2) and seals(2), a quick oil/kero flush then fresh synthetic oil of course. We believe that if this truck had been using a mineral oil I could not have even considered the above option due to likely diff carrier bearings/CW pinion damage or failure. This diff was still trouble free at 1m kms when the vehicle was sold - about 600k kms after the event

I hope this sort of helps!

Regards

Bill Ball

Doug:

Do you have an opinions and/or data on Castrol Syntec 10W 40?

Doug Hillary

Hi Bill,
this oil is sold here under another name Castrol Magnatec 10w-40 and is a service fill for older cars at some Porsche Dealers. It has been sold here since about 2000

It is a Group 3 semi-synthetic oil, ACEA A3/B3 accredited and it probably fits at the "minimum" end of Porsche's engine oil specification. It is really an OK product for a 928 (subject to very low ambient) but typical of some Castrol oils it tends to create a colouring of harmless varnish in the long term
My car was on this oil prior to me purchasing it from the original owner. It had always been serviced from new by the selling dealer

Regards

jserio

Thanks Doug, It does make somewhat of sense. I am using M1 5/30. Of course you here much buzz but where does the m1 5/30 fit in the spectrum of things? I was going to use 5/40 but they were out at the time. Whatta a think?

Bill Ball

Doug:

It sounds like Magnatec is what's called Syntec Blend over here. I believe Syntec is a full synthetic.

It's funny how Castrol is completely different US versus other sites - Names all different, viscosity ranges don't match up. Hard to figure which is which. I would say the R synthetic is the same as Syntec here, but I can't be sure.

US:
http://www.castrol.com/castrol/subse...tentId=6005246

Australia:
http://www.castrol.com/castrol/produ...tentId=6008598

Doug Hillary

Hi Joe,
IMHO M1 5w-30 should NEVER be used in any 928! There is one critical reason for this - Porsche have determined that an oil with a High Temperature High Shear (HTHS) viscosity above 3.5cSt is NEEDED for their engines and retrospectively to all engines built after 1973!.

The HTHS viscosity is cyclically measured at 150C and determines to a large degree the "thickness" of the oil film at many points around the engine - valve gear, cams, crank bearings, ring bore interface and etc.

M1 5w-30 has a HTHS vis of ONLY 3.08cSt!
M1 0w-40 (Porsche factory fill) has a HTHS vis of 3.6cSt and Delvac 1 5w-40 has a HTHS vis of 4.1cSt

IMHO some 928 engines have failed because the oil used did not have a robust enough HTHS vis amongst other things

If you already have it in your engine drive a little more conservatively until the next "shortened cycle" oil change. M1 5w-30 has the lowest Flash Point of all current M1 products so you may use a little more oil too - watch the level!

Regards

jserio

So is 5/40 Ideal then. The level has been real good. Haven't lost any at least since the change 2-3k mls ago.

John Veninger

Magnatec is branded as Startup in the US.

Randy V

Doug - how does Mobile 1 SuperSyn 15W50 compare? That's what I'm running in my car now. As the temperatures here typically range from 50-80 year 'round, I'm thinking that this is a good weight for this climate.

Doug Hillary

Joe,
yes I believe that the best engine oil for a 928 in reasonable order is a modern 5w-40 synthetic in most climates. When changing from say a 20w-50 mineral oil there will be a slight loss ( perhaps 1bar) in hot idle oil pressure (flow will still be the same). Hot OP at 4000rpm should still be at 5bar

John,
so what is the relationship now in NA to these three excellent Castrol products;
Castrol Start up,
Castrol Magnatec, and,
Castrol "R" (or RS) 5w-40 (fully synthetic),
are they all sold there and what is the product overlap?

Of the above we get (amongst many other Castrol oils);
Magnatec 10w-40, and
"R" 5w-40

and both of these have a good reputation here

Randy,
M1 15w-50 SuperSyn is Porsche Approved and is an excellent product and suitable for use in your climate. It has HTHS viscosity of 5.11cSt. It appears to be the most commonly used oil amongst 928 owners worldwide (as a 5w-50 in OZ and Europe).
A 5w-40 synthetic oil will be best for your GTS - that's what it left the factory with when new

The temperature here where I live is from about -5C(23f) to 42C(107f) at the extremes but mostly 10C(50f) to 30C(86f)

Regards

John Veninger

Doug,

Magnatec was launched in the US under the StartUp name.

Castrol RS is in the US as Castrol TWS 10w-60 sold via BMW dealers. This is a very good oil.
http://www.unofficialbmw.com/images/SBS1996-110796138_A9.pdf#search='castrol%20tws'

The only 5w-40 Full Synthetic fom Castol in the US is Syntec. Also sold through VW dealers.