All of the above and more is why what oil to use is often debated.

Porsche comes out with a list of approved oils about once a year. 0W-40 was put on the list in 2001. 5W-40 was put on the list in April 2007. The list for 2001 said Mobil 0W-40 was now going to be the factory fill.

Back then 0W-40 was hard to find, unless you bought it from a Porsche or Mercedes dealership. You could not find it on local auto parts shelves. In my area there is a local Mobil distributor who would order a few pallets and that is initially were the local guys got it. Back then Mobil said it was not going to make this a consumer oil. I forget if Mobil or the distributor told me this. Something changed because after a time it started showing up on shelves, but you had to hunt at different stores.

Even before then, it was said 10W-40 was the factory fill, but it was not sold in the US back then. People would try to replicate it by mixing equal parts of 5W-30 and 15W-50, as those oils were sold in the US. In the US Mobil now sells 10W-40 as a "high mileage."

Oil is a funny business. Mobil has the lion's share of the synthetic market. Mobil makes enough money that they can pay manufacturers like Porsche and Corvette for a sticker on the car.

M1 0W-40 is fine for the car.

So is any QUALITY SYN with a 5W-40 rating.

Not to worry.

I just searched for M1 0W-40 at my local store. No luck!

Will there be any measurable impact on cold weather starts / cold weather lubrication performance (and I mean COLD - 10 degrees F or less) between 0W-40 and 5W-40?

Not really.

Jeff, thanks for your informative post. Q: when you say that a particular grade was put on the list, does that imply that that grade was applicable to the porsches sold that year? So, for instance, per your above post, 5W-40 is (one of) the recommended grades for porsches sold in 2007, whereas 0W-40 is (one of) the recommended grades for cars sold in 2001.

Thanks!

PS: I'm getting the itch for doing the OBD hack on my 01 (I need the temp to tell me whether to turn on the heat or the ac :) ). I'll send you a note when I run into trouble.

The last few lists of approved oils state that they are retroactive for Porsches made since a certain date, excluding certain models.

The bulletin/list issued April 11, 2007 states that the list is for all Porsches made since 1984, except for the V6 Cayenne.

The prior list was issued July 28, 2006.

So what happens when an oil is on the list, then that oil is taken off the list when the next list comes out a year later?

Everyone has to go to their dealer and immediately change their oil - just a joke.

The dealerships have to throw away all their oil inventory if the oil was on the old list but not on the most recent list - just another joke.

The bulletin issued April 11, 2007 states that the remaining inventory of engine oil specified in the prior list (July 28, 2006) can be used up until June 30, 2007 if the oil is not on the April 11th list. Now, figure that one out.

Then, the April 11th bulletin/list states that Porsche has reached an agreement with the oil companies. An oil approved by Porsche is valid for 2-3 years. After that time Porsche's approval is revoked unless an extension is requested by the company.

Being a cynical Boxster owner, I wonder what it take$ to get on and $tay on the li$t of oil$ approved by Porsche.

I use Redline 5W40. Great oil. I put this in during October 2006. I have an oil change scheduled in 2 weeks. I'll have just over 9,000 miles on this oil. Never added even an ounce of oil during this time period.

Red Line is one of the last real syns left on the planet.

Group 5 basestocks all the way.

I use this in my Sportster and used in my Box.

Good stuff, not cheap.

:)