I've seen some board traffic on this before but without a real definitive answer. My dealer says 5W-40. My local motorsports shop says 0W-40 (which is I think what the factory ships). The guy I bought my GT3 from (and who is a serious track guy) says 10W-50. I'm confused and would greatly appreciate anyone who could clear this issue up.

 

Mobil one 0W-40

 

There is an article in Excellence(april, of last year)page 34 on why you should be using OW-40. I would read it before changing to 5W-40, or anything else.
Rich

 

For driving hard in 100+F, here in the hot socal summers, 15w-50 is perfect..

 

Thanks Rich, I should have that Excellence issue and will look up the article. As you can see from the responses already recieved, there does not seem to be a consensus on this question.

 

does anyone have first hand experience on if there would be a decrease in performance in anything other than 0w-40, regardless of brand.

 

The MOTUL 300V 15W50 I can't keep on the shelf. Been very happy with the feedback I am getting from customers. Will try the just received 300 V Le Mans 20W60 when it gets hotter down here.

Theo

 

I use MOBIL ONE 15-50 in everything I have-race MX bikes lawn mowers Porsches. But talking to a noted TT expert that I trust very much he said here in the desert I should use 5-40.
its 110-120 in Aug. here.
I have ONE HELLUVA time finding it. But this weekend at Fontana Performance
has a new oil NOT mobil in 5-40 and they said it was a good oil fully synthetic.
I have to do some research but they said it was good.

 

+1. I also saw that long article on oil, and I thought i knew it all. bottom line 0W-40 is what Porsche recommend and why would we think we know better. Most damage to motor is at start up thus 0W is important. so you have to balance your damage on motor at start up and your street use. If you were a race only vehicle then maybe the 50 wt oil would be recommended. bottom line lower wt oil lubricates the motor better because it is thinner and gets to where it has to go faster and freer contrary to what you would think that thicker oil is better it is not necessarily true. Thicker oil takes longer to lubricate and is only better at a high temp a temp that your street car rarely sees.

 

Aside from what the manual says it depends where you live. 0 to 15 is a huge difference if you are running the car in winter, 15 would be like tar. In the south though the higher viscosity 40 should be suffice. I guess if you were on a track in 100+F maybe 50 wouldn't break down as soon. That being said, I personally think you could probably run the stock oil for 60,000miles.

 

I just read the Excellence article you guys are talking about and, as you pointed out, the author is clear about why 0W is indeed critical to our engines. For example, he specifically points out that the design of the Variocam system is dependent on the thinner oil for proper functioning. Even though my dealer used Mobile 1 5W-40 in a recent oil change, I'll be using 0W-40 for top ups from here on out and change back to 0W-40 at the next opportunity.

 

i use valvoline vr1 racing 20w 50 (in my turbo)that is what my tunner recomends and thats what i use , as i trust him fully . he said he has seen engine failures with the 0-40 mobil one , and to stay away from it.

 

Suncoast Porsche recommends 0w-40

 

I am still amazed at the diversity of opinion on this issue. Surely there must be a "right" answer. Why wouldn't we assume that the Porsche recommended viscosity would be correct?

 

Mobil 1 5-50