Why no Porsche recommendation for 5w-30?

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Originally Posted By: Art_Vandelay
Originally Posted By: dparm
I'm with you Doug. Why does everyone think the engineers at car companies are morons who make arbitrary decisions?


Now come on. We all know that, after throwing a few back, the average backyard mechanic knows more about viscosity than those lucid, control freaks from Zuffenhausen.


funny!
smile.gif
 
Originally Posted By: Doug Hillary
Hi,
drkbrent - No SAE30 lubricanst have been Approved for Porsche designed engines since 1999

The Porsche Approvals process for these engines is very demanding especially in the areas of viscosity retention and foaming controls. This of course includes the minimum HTHS vis. of 3.5cP

And yes the Porsche Engineers know best IME


Doug, hope the floods missed you mate! I understand the SAE 30's haven't been approved by Porsche for a long time...I guess I'm not asking my question correctly. I'm just curious as to WHY the 30 weights haven't been recommended considering the Bugatti, Mercedes V12 twin-turbos (and others) have a 5W-30 in their veins from the factory. My Porsche doesn't produce the same levels of power, torque, heat, etc. that these other engines produce. I've only taken the Porsche to 171 mph for a brief moment (always hit too much traffic) and have seen the Bugatti hit 230 mph for a few minutes)...what is it about my little 3.6 litre twin-turbo engine that is different? I need to read the other posts in the thread...maybe someone has answered...(and I have a personal theory as to why)...I'm just interested in what some of the members here think (they know a heck of a lot more than me)! Thanks.
 
I have several cases I need to use...don't track the car, can't drive it over 100 mph for extended periods of time...that's really the only reason.
 
Dave recommended their 0W-40 (said the 5W-40 would be fine also). I use the Lubromoly 5W-40 Synthetic in the summer. All the actual oil company guys will ALWAYS recommend the factory recommended viscosity (from my experience). Probably a smart thing from a liability standpoint.
 
Originally Posted By: Corvette Owner
People who think they know more than the Car Manufacturer's engineers and designers make me laugh ! Especially Porsche, THEY KNOW what they are doing. Engine tolerances and design mean more than just oil temperature !


Mr. Vette, hope you didn't think my post was insinuating that I knew more than Porsche...far from it! My question was one of simple curiosity...just want to know if anyone knows, specifically, what is different from the Porsche engine vs. those other engines?
 
My guess would be that a 40w holds up against fuel dilution longer than at 30w since it starts out thicker. If Porsche uses low tension rings like VW, dilution could be a bigger issue than in other motors.
 
Originally Posted By: ARCOgraphite
Art, you are ON today
smile.gif



I wasn't kidding ARCO lol! Good to see you my friend.
 
This kind of question is often asked but the science behind is often not understood well. I just happened to find an interesting article earlier that discusses viscosity and lubrication of machines. It's a snippet from a book, apparently.

http://www.bardyne.com/Documents/B3samp01.pdf

Changing the bearing diameter and bearing load surface length greatly changes its load carrying capability. There are also many other factors, so when considering why engine A is supposed to use a different viscosity than engine B, you need to know a lot of design details, which are usually difficult to find.
 
In addition; while many other engines may put out the HP/L that Porsche does, I;ve seen not one finish a 12 or 24 hour race. I have seen several do top speed runs and many 0-150 but, never a 6 or 12 or 24 hours at full racing. A simple quastion asked and answered because Porches data is beyound backyard machanics.
 
The most demanding job for oil in a SI (spark ignition) engine is the oil film strength for the crankshaft. This receives the brunt of the explosions from the cylinders. I suspect that a flat 6 cylinder engine may have more "impact" loading than V8, V10, or V12 engines, since the impacts are 180 degrees opposed.
 
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Hi,
drkbrent - Porsche did in fact use SAE30 lubricants as a factory fill. A 10W-30 was used in the '91 (or so) 928GT (the first car to receive a stynthetic engine lubricant as a FF). This was quickly changed to a 5W-40 - within a MY!

M1 0W-40 became the FF around 1997

SAE30 lubricants were on the 1999 (now A40) List (retrospective to MY1984) for the last time. Only one SAE50 lubricant survived after this point as I indicated earlier M1 5W-50 - it is still Approved

These were specified for use as follows;
Mineral oils
-15C to 30C - 5W-30
-15C to 20C - 5W-20

Synthetic oils
-15C - 80C - 0W-30 (Castrol's Formula SLX (GC) was one!

I provided my grasp on this in an earlier Post. Primarily IMO it is to do with viscosity retention, foaming and the need for a specific and enduring minimum HTHS vis. of 3.5cP. A consideration was allowed for the backdated Approvals to MY84

The Porsche Engineers do place a lot of value on lubricant selection and especially like MB on the use of the manadated viscosities
 
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I have a 2004 911 turbo. The factory initally recommended 0W-40, but lately bc of intermediate shaft issues, many are going to either M1 TDT 5W-40 or 5W-50.

I have done also myself. The difference in engine noise w TDT vs 0W-40 is not slight. Must be the extra ZDDP I suppose.....
 
I thought that speaking of any issues about Porsche is voodoo and not allowed to be heard by us commoners. IMS issues missed by those superior German Engineers? trust their oil recommendations now?
 
Originally Posted By: unDummy
I thought that speaking of any issues about Porsche is voodoo and not allowed to be heard by us commoners. IMS issues missed by those superior German Engineers? trust their oil recommendations now?



unD -

Well, understand that Porsche engineers are under the same EPA constraints as any car manufacturer, so their oil recommendations for US cars may not be entirely based upon what is mechanically best for the car.

Porsche engineers are good - some of the best in the world IMO. What other car company can produce a car that will run for 300,000+ miles while putting out super-car performance? However, there is just no way that they can know all about what will be best for a given car over its entire life.

To the original poster - my car is a generation older than yours so things could be different, but everything I have read lately points to a heavier weight oil in these cars. Go to Rennlist if you want more information, but this is coming from the guys who are working on and rebuilding these cars for a living. There is just no way I would run a 30 weight in my turbo knowing what I know now. No way.
 
Hi,
unDummy - I'm sure you can speak about Porsche just like you can about any other Brand

It is wise I believe to understand what the IMS and RMS issues really were, the reasons why, and how they were attended to. This has been covered here before - I for one will not be revisiting it again - and I can say taht at least one of them was really quite minor in the scheme of things!

I will state again however that using an Approved viscosity (especially via TSBs) is very important
 
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Originally Posted By: Corvette Owner
The most demanding job for oil in a SI (spark ignition) engine is the oil film strength for the crankshaft. This receives the brunt of the explosions from the cylinders. I suspect that a flat 6 cylinder engine may have more "impact" loading than V8, V10, or V12 engines, since the impacts are 180 degrees opposed.


Now THAT is what I was looking for...this makes sense to me. Thanks for all the responses guys!
 
I just want to know where around Baton Rouge you can drive speeds like that. Considering the conditions of the freeway that runs through Baton Rouge, anything over 70 would worry me.
 
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