IrocMan

Hi Folks,


After a while too far from a Porsche steering wheel I'm back with a 2003 Carrera 4S upgraded with a PSS9 suspension. I just bought it last week and I already simply love it - it's a bit heavy but the engine is fantastic and the chassis even more precise than I would have expected.
It took me more than 4 months to find the perfect jewel. I saw many 2002/03 C4S and only two appeared totally sane for me, including that one. The only thing I didn't like is the Turbo tail - that will be removed for the original parts during its next service.

I have two questions :

1) In the fuel door there is written "R+M/2 = 93 minimum".
All I can find in my area (SF Bay) is 91. In Europe we use to have 95 and 98, is it the same way to calculate the quality? Does it mean that gas here is crappy?

2) What oil is the best for the 996 engine?
It never freezes here, it's even hot these days.
What do you use for your N.A engine ?

Actually I have a third question even if I don't like to ask this : where to service it ? I'm in Los Gatos and work in San Jose. I'm good with independents who have proven their qualities but don' t want to pay 2000 bucks for an oil service

Thanks in advance for the info. I'm going to take picture and post them here

-Luc

ejdoherty911

91 octane is fine. Oil, Mobil 1 0w-40

htny

A lot of guys in California run a couple of gallons of unleaded 100 octane in a tank of 91, but I was fine with straiht 91 when I kept the car in LA for the first half of the year. The car definitely felt like it lost a little pop after the first two tanks, and there was a noticeable difference after switching back to east coast 93 octane, but that's purely qualitative, and it's not going to kill you or the vehicle.

RE: comparative octane ratings, the 95 and 98 numbers overseas are Research Octane Numbers, or RON, which are comparatively higher than the Pump Octane Numbers (PON) in the US and Canada

to further add to the confusion, PON is actually a loose average of RON and Motor Octane Numbers (MON)

so 93 PON here is roughly equivalent to 97/98 RON in Europe
91 PON here generally closer to 94/95 RON in Europe
etc

Oil is a tricky subject, search this forum and you'll find there is a lot of debate. Check your Porsche recommended oil list, pick one, and go.

Van

They don't have 93 in CA? They have it in NY (Mobil comes to mind). And Sunoco has Ultra 94.

p.s. I'll stick my neck out and say that I've been happy with the recommended Mobil 1 0W-40

Phil G.

I run Sunoco Ultra 93 (or 94), and agree with above that Mobil I 0-40 is fine for the car.

Tippy

After 4 full tanks full of gas ran through his 996 and 1 oil change, Phil is an expert.

pszikla

I knew Tippy couldn't resist Phil's comment!!!!!!!!

Phil G.

Make it 3 tanks of gas and 1 oil change. And they say that Porsches are expensive to maintain! Hah.

discoganya

Ninety one is the highest octane rating sold retail in California. BTW, there is a station at the intersection of Santa Teresa and Cottle in San Jose that sells 100 Octane gas.

As for indy mechanics ... there are plenty of those in the Bay Area. See this list: http://www.pca-ggr.org/files/doc/LOCAL-MECH.doc

I have been going to CT Automotive in Campbell for three years now. All I have is praise for them: Tony & Chris are top rated guys.

salayc

For what it's worth, Porsche just admitted that lower octane fuels will not damage their engines or affect warranty. There have been a couple of lawsuits against car manufacturers who do not honor warranty claims because of fuel.

salayc

European 95 is the same as US 91. RON method vs. MON method.

IrocMan

Hi guys,
thanks for the replies.
I understand a bit more now and will keep the equivalence in mind (EU 95 RON = US 91 PON and EU 98 RON = US 93 PON) just like one yard v.s. one meter... or even one dollar v.s. one euro... but why is everything better in Europe ?

I use Castrol 20w40 in my 964 and 10W30 in the BMW.

A friend who is an engineer at Unil-Opal (Shell) told me one day that "top end general purposes oils" like the Mobile 1 0W40, even with their "supersyn" components have a too wide range to be perfect and recommended to use 10W30, 20W40, etc... depending on the temperatures.

He was our advisor in endurance championship where I used the opal jec (equivalent of the Shell helix I think) in 10W30, but I've always been confused by the fact that at the same time, Unil-Opal advertised their 10W60 to be the best protection...
So I actually don't know what to think and will use Mobil 1 since it seems to be good for us.

Oil, gas and tires are points on which I'm really sensible. While gas choice is simpler, discussions about tires and oil choice are always endless.

@ Hans and disco:
Does it make sense to use some 100 octane gas in our catalysed engines ? I thought these were very toxic gas, even the unleaded one that contains phosphorus or something like that, which would kill our catalytic converters.
I used 100 LL (leaded aviation fuel) when racing in Europe. No catalytic of course

thanks for the info

-Luc

Tippy

Actually, it's Wayne's job

Ray S

I'd use one of the oils Porsche recommends on it's list. Listed below, are a few reasons not to use heavy oil in your Variocam Plus car.

The April 2007 issue of Excellence Magazine addressed the "oil" topic. Two technical experts claim that newer Porsches require the thinner oil to ensure proper VarioCam function.

On page 34 a reader asks a question about using 10W-40 oil (for a Boxster) in Florida vs Mobil 0W-40. He is concerned about using the 0W-40 because 10W-30 or 10W-40 is a "more common fill" in Florida (he also asks about break-in). The response from the Excellence technical expert was as follows.

"Those who suggest higher viscosity oils usually don't understand the whole problem. Oil in engines is no longer just a lubricant. It is also a coolant for the engine as well as a hydralic control fluid for all of the things like VarioCam Plus, hydraulic lifters, and similar systems. If the oil is too high a viscosity, it can affect the way those circuits operate.
The 2001 996 Turbo was the first Porsche to use the VarioCam Plus technology and a friend who works as a dealer technician told me that one of their technicians spend the whole day trying to diagnose a running problem caused by an owner who hadn't trusted Porsches factory fill and thus changed his oil to SAE 20W-50. The heavier oil totally confused the VarioCam plus system and the engine ran poorly.
All of these devices have been designed to run with the SAE 0W-40 oils or other oils that Porsche recommends. Use only those oils recommended in your owners manual - SAE 0W-40, SAE 5W-40, or SAE 5W-50. Porsche is so sure about this decision that it came out with a bulletin recommending these oils for all of its older models as well."

On page 169 (of the same issue) Porsche tech expert Jim Pasha dedicated his entire "Tech Forum" article (6 pages worth) to "Oil". I'm not going to type in all 6 pages of material but I will quote a few short pieces of what Jim reports in his column (he covers a lot of ground in his article).

"Why does Porsche specify such a low lower viscosity rating? The answer comes in two parts. First, in a quest for better fuel economy and longer engine life, Porsche engineers use bearing and cylinder-wall clearances far tighter than what they used previously. This creates less internal drag on components, and lighter oil is more compatible with tight tolerances."

He also says;

"In the latest Porsches, which use 0W-40, the thinner oil is critical to delicate systems that use motor oil as a hydralic activator. VarioCam Plus uses tiny "shafts" of oil created under high pressure to help the system alter valve timing. It is a trick system but it REQUIRES thin oil to work properly

Finally here is what Porsche says on the matter;

http://www.wrightune.co.uk/downloads/approved_oils.pdf

htny

almost all 91 PON gasoline sold in California has a "blend" of oxygenators like toluene and even eth/meth to increase the knock rating artificially, so no matter what you do you're stuck with those factors and so are your cats. Not to treat the matter flippantly, but your cats are firstly designed to handle a wide range of contaminants and furthermore are covered under federal and state emissions warranties for significantly longer than the vehicle. Look inside your owner's manual for your specific vehicle's emissions warranty parameters.

I never ran the 100 in the 996 because I knew I wouldn't do it often enough, so I decided to let it detune to 91 while I kept it in CA. When I've purchased it in the bay area in the past, it's been at a 76 in Palo Alto whose intersection I can't remember, however the internet is full of sites which tell you where you can get 100 octane in your neighborhood.