DarylJ

Since those guys have made their recommendation and likely even seriously thought about this motor, most of them have a whole lot more miles on them than they were able to simulate before arriving at their numbers. So we have a variable of wear characteristics that they didn't know about.

The second variable is that we've been through about 5 different oil standards since then. Oil has come a long way, and, not always for the better depending on your engine (ask the air cooled guys how much of an oil selection they have that has enough zinc in it still).

Yes, it's the same car and the same book. But other things have changed.

hacker-pschorr

This is where the discussion usually splits the track "botique" oils from the street - certified - blends.

Just ask this guy:
https://rennlist.com/forums/5477214-post12.html

(am I really linking to a Kibort oil post........)

How I understand it is the greater difference between the two numbers, the more modifiers need to be added to reach the "hot" viscosity.
The more modifiers, the greater chance the oil will break down under extreme / extended use.

I know quite a few track junkies who run straight 50 or 60 weight oil for this reason.

bearone

here ya go.

yes, oils have changed but just how has the motor were dealing with changed?
basic function/design is the same even with upgrades.

87951
95sl320 dd

OntarioTurbo

My owners manual for my '86 951 says to only use oils that meet the specifications designed by Porsche. In 1986, at the time of printing, that could have been dino oil or synthetic. But even then Porsche did recommend "Low-viscosity" oils. The manual goes on to say "Low-viscosity oils reduce internal friction in the engine. These conditions are currently fulfilled by synthetic or hydrocrack low-viscosity oils". It also says "the degrees of quality in an oil are expressed by final letters in alphabetical order: The requirements for Porsche engines are API class SE/CC to SF/CD (maybe more important than oil weight).
Fast forward 23 years and we have new Porsche recommendations. The following was taken from the "Porsche Manfacturer's Certificate"

Oil Quality: The engine oil is not only a lubricant, but also fulfils many functions at the same time such as component
cooling, component cleaning, and protection from corrosion. To be able to fulfil these tasks, the oil
contains specially developed additives.
Mineral oils are extracted directly from crude oil. Using a series of chemical processes, these oils can be
further refined (hydrocracked oils) or completely transformed (synthetic oils). These oils provide a higher
level of performance than pure mineral oils.
Only hydrocracked or synthetic oils are now approved by Porsche.Vehicle Type: All Porsche standard-production vehicles with the exception of the Porsche Cayenne V6 3.2
and V6 3.6 DFI.
The engine oils for the Porsche Cayenne V6 3.2 and V6 3.6 DFI are listed in a separate bulletin.
Model Year: As of 1984

As you can see most of our cars fall within the year range of this new report. The report goes on to list the approved oils. All the Porsche approved oils are 0W-40 or 5W-40 except for one, which is 5W-50.
From this I can conclude that Porsche wants us to use synthetic oils. The weight of oil or viscosity is left up to you, but they reccomend 0W or 5W-40. You may find however, that a different wieght oil works better in your particular car or for your personal driving habits.
Oil technology is continually evolving. Porsche acknowledges that, why shouldn't we. A lot of research has been done in the past 23 years. Keep an open mind, learn as much as you can and make dedcisions that are best for YOU. If you really want to know what's going on with your oil you will need an aftermarket pressure and temperature guage and send in samples of your oil to a lab for analysis. Then you'll find out what's best for your engine.

Mike C.

If you really want to know what's going on with your oil in your engine try an oil analysis lab such as:

http://www.blackstone-labs.com/articles.html

Lorax

There is also the zddp issue to cinsider with our cars.

Lorax

Wear, replacement parts that are not the same spec as the originals, modified engines. Things like that.

DarylJ

I've not gotten a good feel on that one yet. I've found things like:

----
“The new Starburst specification contains two valve-train wear tests. All Starburst oil formulations must pass these
two tests.

- Sequence IVA tests for camshaft scuffing and wear using a single overhead camshaft engine with slider finger
(not roller) followers.

- Sequence IIIG evaluates cam and lifter wear using a V6 engine with a flat-tappet system, similar to those used
in the 1980s.

Those who hold onto the myth are ignoring the fact that the new Starburst oils contain about the same percentage
of ZDP as the oils that solved the camshaft scuffing and wear issues back in the 1950s. (True, they do contain less
ZDP than the oils that solved the oil thickening issues in the 1960s, but that's because they now contain high levels
of ashless antioxidants not commercially available in the 1960s.)”
----

But I'm not sure I'm comfortable with any of the sources I've found as being accurate.

hacker-pschorr

Already mentioned here:

https://rennlist.com/forums/6343075-post32.html

That's the GF-4 classification, mentioned in the link above. This is considered an issue with any car with flat tappet lifters.

Some "boutique" oils have higher levels than others. The non GF4 oils are the old ZDDP levels.

From what I've read, anything over 1,000ppm is where you want to be. There is some debate on weather or not there can be too much. Here is the Mobil 1 spec sheet:

http://www.mobiloil.com/USA-English/...duct_Guide.pdf

All of the GF4 oils are 800ppm or less.

OntarioTurbo

Just to clarify. On the Mobil 1 chart, are the oils that are not listed as GF-4 have high enough ZDDP levels? For example. I see the Mobil 1 0W40 is reccomended for Porsche and is not GF-4. Does that mean the ZDDP levels are high enough for our cars? I read somewhere else that all oils that are rated for diesel use (CF etc., the "C" is for compression ignition) have good levels of ZDDP as well. So one may be safe if you select an oil that is SM/CF rated. Anyone know for sure? Thanks for the chart by the way!

joonas

Look following table Profile column
http://www.motul.fr/motulbaseuk/gab_fiche2.asp

For API marking look here
http://motorcycleinfo.calsci.com/API.html

OntarioTurbo

I apologize. I didn't initially see the nominal Phosphorus colunm (D'oh). That pretty much aswers my own question. Thanks again for the chart.

hacker-pschorr

This is the problem, everyone is looking for an answer that isn't there.
Some "experts" claim ZDDP is only an issue when breaking in a new motor / cam (assuming you installed new lifters). Others claim it's always necessary, meanwhile the experts behind the new oil claim it's all non sense, 800ppm is "just fine" for all engines.

Buy whatever helps you sleep at night.

I know a guy with over 200,000 miles on a 944, never spun a rod bearing, all original. He also never used synthetic oil, changed every 5,000 miles or so.

My 944S had 80,000 on the clock when I purchased it in 1996. In 2001 with 112k on the odo it spun a rod bearing. I only used synthetic, changed every 3,000 miles. Never tracked - autocrossed once (three years before the bearing went).

Diesel's do not have catalytic converters (at least not until recently). Zinc kills catalytic converters, this is why the new oils have lower ZDDP levels.

Mobil 1 Delvac 5w-40 is becoming quite popular with the sports car world trying to find ZDDP oils. It's called "Turbo Diesel Truck" in the chart I posted.

Air cooled motorcycle oil is also becoming popular.


There is also the “theory” that most new cars are coming with super thin oil to save on gas in the US. Various Ford models are sold in the US with thinner oil versus their European counterparts (with the same motor).



I’m not an expert on any of this, I’ve just done a lot of research on the topic and I’m sharing my findings. I use Redline, Royal Purple, and Mobile 1. This year Royal Purple is going to be swapped out for Amsoil or something else I can find locally. Why? The only place that carries RP locally is now charging $12+ per quart.

To bring this up again, $20 buys you an oil analysis from BlackStone Labs. Anyone that is really trying to keep up on this, send in your oil every spring or fall.

EDIT - here is a good chart:

https://rennlist.com/forums/6347084-post17.html

Mark944na86

A list of Porsche approved oils (tech bulletins) for waterpumpers (dated March 2005.)

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

hacker-pschorr

Funny, none of the brands I use are on that list. Also, not one listing for anything 50 weight.