Hi,

How far should a 911 3.2 running on Mobil 1 motor oil (under normal street driving conditions) go between oil changes? Thanks.

 

I bought a '91 C2 a few months ago and filled it's belly w/Mobil One, Adrian from Switzerland finally convinced me!

I have found two different technical advisories that basically differ due to European and U.S. standards, the U.S. version says every 12k, Euro says every 15k.

Being that your 3.2 is a little different in design, my only guess is to change it a little more often? ...maybe every 10k??

But then a lot of those types of decisions depend on how you drive the vehicle...I do a lot of track events, therefore revving and stressing the engine a bit. As I get closer to having 5k on the car and 3 track events since purchase...I'm considering adopting a 5k ritual??

 

Thanks Jeff,

I wonder if the numbers are affected by how long the car sits without being driven. I appreciate the information.

 

It has been well documented elsewhere, that the base oil stock really does not wear out. It's the additive packages that do. They are used up as they combat metal to metal wear, and chemical interaction with engine parts.

A car that is used for short trips, and sits around a lot, needs to have it's oil changed more frequently. This is due to the by-products of combustion not having the chance to be vaporized by higher engine temps. The oil additives have to neutralize these contaminants, and therfore, the oil "wears out".

 

If you read the Porsche owner's manual from a 993 it says 15k. Unless.. it's been hot, or cold, or dusty, or rainy, or humid, or you drive fast, or slow, or alot, or not very much, or you live in Fresno, or you're a vending machine repairman.
So, we recommend 7500 miles, just because the oil hasn't broken down doesn't mean it's a good idea to leave the dirt in the engine that long, and I did see a twin turbo that the owner let go 17,000 mi and the oil had clearly broken down.
What the hell, it's only money, you'll get more in 2 weeks anyway.

 

While the additive package does breakdown, the basestock does as well - otherwise there would be no advantage to Mobil 1 (a synthetic basestock).

Because of its resistance to oxidation, thermal, and mechanical degradation, Mobil 1 offers several advantages:
(1) longer intervals between oil changes
(2) better stability at high temperatures (remember the frying pan in the TV ad)
(3) higher sheer resistance

For a 911 used in daily driving with regular oil changes of 5-6K miles, I can't see spending the money on Mobil 1. A synthetic blend or even a high quality petroleum-based oil will serve you just fine.

For turbocharged cars, I would recommend Mobil 1 - just because of the temperature and stress.

 

Thank you all for the excellent information.

 

By the way, I didn't see Adrian from Switzerland weigh in on this topic yet...

 

I wonder, is it worthwhile for Mobil 1 users who "want to have their cake & eat it too", to change the oil filter at 1/2 the oil change interval? Would this assure that the oil remains clean even if the changing interval extends to, say, 7500 mi?

 

Just as a related aside, I ran across this in pulling material together for the 911SC FAQ. Interesting to note that almost all, if not all (don't know about the Exxon oil) oils currently recommended by Porsche are synthetic:

In a March 2000 Porsche Technical Bulletin, summarized in "Porsche Approved Engine Oils" by Allan Caldwell in Porsche Panorama, October 2000, p. 82, the following oils are approved by Porsche for all 4,6, and 8 cylinder Porsche's from 1973 to current models:

Manufacturer/Name Weight

Castrol/Syntec 5W-50
Exxon Superflo Supreme Spec . 15W-40
Mobil 1 5W-30, 10W-30, 15W-50
Sun Oil/Sunoco Synturo Gold 5W-40
Texaco/Havoline Formula 3 Synth 5W-40
Valvoline/High Performance Syn. 5W-30

Porsche approved the use of synthetic oil in it's engines in 1980, but cautioned that normal oil change intervals should be followed. The factory has been filling it's new engines with synthetic oil since August 1992.

 

So Bill, what then is the normal interval for the 911? Does it vary?

 

Bill,

I don't see any Kendall oil on that list.

The reason I ask is that I recently purchased an '81 SC with 130k miles on the clock. I have used Mobil 1 in my other cars from 10k on, therefore I have no experience using a synthetic on an "old" engine. From all the service records, the wrench used Kendall oil exclusively. Would it be better to continue using Kendall? Other than having two successive oil changes when going to a synthetic oil, are there any other things I should be aware of when going from dino juice to Mobil 1 synth? What about the effect on old seals?

Any info would be great.

Cheers!

 

Guys, I do not weigh in unless I feel I can offer constructive answers.
The 3.2 Carrera and its engine, oil etc is not my area of expertise. The 3.2s were all delivered ex factory with Dino oil.
The 964 series is a completely different beastie.
Now with that said, I recently changed my 944 over from Dino to full synthetic and will run it 20,000klms which is the same as my 911C4 recommendations.
I also run 5W 30 which most of you will not wish to run unless you live in a cold climate.
Economics also plays a role. 4 or 5 Dino changes for every full synthetic change.
The oil you have to worry about if your 911 or any other Porsche sits around a lot is the gearbox oil. I wonder how many change gearbox and transmission oil and how often.
Ciao,
Adrian who lives in Switzerland but not from Switzerland
911C4
944

 

IceBlueSC,

I have -70's 911 and previous owner had used Gastrol STX? (10w-30) oil and when I got the car I started using Gastrol RS 10w-60 (oh yeah baby!), but anyhow sometimes if you start using syntetic oil it can cause some oil leaks. I'd say, use very good (that Gastrol RS 10w-60 is excellent choice!) oil, It keeps your oil pressure up and is really great oil for older 911. Since you live in warm climate, that will work all year round. Change it (and filter!!) about every 5000 miles and that's it!

 

I just bought my first 911, and have just changed the oil. The book says straight 30 I think (the car is a 1970 t model) and I figured that 10w30 would suffice. I bought Castrol GTX. I have since been told to run 20w50 in this car, and to drain the 10 30 right away.

Well, I just put 9 litres in it and am not planning on racing it or anything. will this grade be ok in my car? Is it too thin? I will not be driving the car in below 33F for sure.

Also, I tried to get the SWEPCO gearbox oil locally through a friend who owns a heavey equipment fleet service shop and he had'nt heard of it. I asked him to look into it for me through his sources and he said it stands for "south western petroleum company". He gave me chevron "delo" ESI 80w90 for a fraction of the cost and said that this is a good product that he uses regularly.

This is the link to its specs: http://www.chevron.com/prodserv/nafl...rodspec_fs.htm

Does anyone else use this, or any comments? I will let you know how it works.