Where can i get my hands on list of Porsche approved oils??

 

google. It's also in your owners manual

 

Loren on Renntech keeps a great updated list for his Members.

 

Roger that

 

I don't claim to be any oil expert but i am aware viscosity is a key component where high temps and engine protection is concerned.

Anyway, I called up the Mobil tech today to get a clearer understanding of the differences in the Mobil 1 grades they offer for the 911 turbo. In the process I also checked with my service tech to confirm the grade they last used, which was a 5 -w50 instead of the previous 0-w40. So sorry guys I made an error in my previous post re my current use of the 5/40 Mobil 1. That is actually a grade that doesn't exist in Mobil 1's line-up. Here is the line with the 5w-50up:may be of some interest: http://www.mobil1.com.au/products/product_5W50.aspx

The Mobil oil Tech informed there is a 0w40, 5w30 and 5w50 specified for use in Porsches.....but again, no 5w40 grade.

As suspected there is a difference between the 0w40 and the 5w50 even once the oil reaches operating temps, and this is to do with both centistoke and weight.

EG the viscosity index for the 0w40 and 5w50 is 185 vs 179 respectively so they are very close although the 0w40 edges out the 5w50 by 6 points. The centistoke for the 0w40 at 100 deg C is 13.5 vs the 0w50 at 17.5 giving the 5w50 a slight lead. So they are both extremely good oils and quoted as far superior than any mineral oil on todays market.

The 0w40 is recommended by Mobil and Porsche as the optimum grade for the 911 turbo engine as it has the highest overall performance spec out of ALL their offerings. As you can see by the above info it has a very high viscosity centistoke rating and, the best ability to flow through the engine faster without sacrificing viscosity than the other offerings due to its lighter 40W. The faster flow is quoted by Mobil as being better under high performance conditions due to the faster flow than the 5/w50. From my understanding the faster flow would enable quicker removal of heat from the bearings, delivering fresher less heated oil in place. The 5w50 oil under the same conditions has a slower flow therefore will not perform quite as well in that regard. However as both have excellent viscosity the protection is extremely good anyway.....which is probably why the 5w50 still enjoys Porsches own highest A40 spec rating even though it misses out on the faster flow rate capability. Slower too when cold but still not as fast as the ow40 when hot either.

He wasn't able to explain to me why one variant would burn off any faster than the other but then again he is an oil expert not a Porsche or engine expert. I also noted he was referencing most of his information from charts and not from his head. So i assumed his qualifications were limited in so far as being able to offer qualified comments to why one oil would be burning quicker than the other in practice, even though he he felt theoretically they should burn at the same rate.

With regard to the engine side of things I have found from my experience being in the engine industry that an engine operated with a thinner lighter weight oil has a general tendency of burning more oil off during the combustion cycle that one with a heavier weight. The amount burned also has a lot to do with the quality of the oil and the viscosity too, so that said, with the Mobil 1 and knowing it has an extremely high viscosity rating, and being a top shelf product, by rights it should not burn away so easily at temperature because the viscosity should be resistant under high temps (altho that said viscosity does reduce the hotter the oil gets over the centistoke mid point. However when you look at the 5w50 which has the same premium level of viscosity rating (in fact slightly higher) combined with the heavier weight/ slightly slower flowing oil, to me it is logical that if one type was to burn faster it would be the lighter weight variant. Again, the hotter the oil becomes the thinner it gets and therefore becomes subject to more dissipation/burn off.

I am however aware that oil viscosity recovers very fast once the loads ease (along with the oil temps etc), therefore viscosity does not remain diminished for very long during normal operation. It's only when high loads are sustained (which results in higher oil temps) such as in a track environment that the risks increase for bearing or engine failure due to the viscosity reducing...which occurs from higher oil temps. It is also in this type of environment that you will experience a faster rate of burn off too. So the operating conditions and environment are relevant factors where oil consumption is concerned, meaning there will always be variation between engines.

So to conclude. Which is better to use? The 0w40 or the 5w50? Well going by Mobil technical and Porsche, the 0w40 is the better because it is the highest performing oil. The next best would be the 5w50 and in my experience so far uses less than the ow40, not that i was using much anyway, just less with the 5w50. That said, and oil consumption aside, the 0w40 is the better oil especially if you intend track days and sustained performance usage.

 

In our main Porsche Service Center only 5W-50 Mobil 1 is on display for purchase (1 litre bottles) and also that is the oil they put in the cars during service.
Haven't seen 0W-40 ever.

What about 10W-60 Shell racing oil? I had it in my Audi TT RS.

 

Awesome, thanks man!!!

 

I use 0w-40, because Im most worried about engine wear at cold start up.
Even this is too "thick" when cold.

0w-60 anybody?

 

0W is the cold viscosity - can't get less than that.

 

of course

 

In Belgium Porsche used 0-40 for a long time, recently they changed to 5-50.
When I had my Porsche serviced it came back with a new sticker:

 

Interesting.

 

Forgot to mention during my second call yesterday we discussed the recommended oil change intervals mindful there has been a lot of discussion on this topic. He said the Mobil 1 oil is so high tech it definitely has a life of 20,000kms or 12 months (or whichever comes first). He said he was aware of pedantic owners changing the oil at 5000kms and commented that changing it at less than 10,000 km usage would be a complete utter waste of money. And, that applied to vehicles doing a few track days as well as a lot of sporty driving, the oil would still be good for the 20,000.

 

"The Mobil oil Tech informed there is a 0w40, 5w30 and 5w50 specified for use in Porsches.....but again, no 5w40 grade."

Time to get a new Mobil Oil Tech. The one you have doesn't know what he's talking about.

For Porsche sports cars (circa 1985 and newer) there are several brands of 0w-40 oils, several brands of 5w-40 oils, and one brand 5w-50 oil approved.

 

This Mobil oil tech appears to be woefully ignorant about different usages, environments which can affect oil change interval requirements.

Further this Mobil oil tech is also offering advice or an opinion that is contrary to Mobil's company policy IIRC stated in its online literature and that is it recommends one consult with the car maker for not only what oil to use but also what oil change interval to follow.