I bought my '09 turbo last July, have other cars, and live in Denver where it is known to be cold and snowy; so in 7 months I've put 348 miles on this car. At the one-year mark there will still be well under 1,000 miles on the oil that's in the motor. I do my own oil changes.

EVERYTHING I read says change oil every X,XXX miles or one year. Porsche recommends this for obvious reasons, but why do all forum members repeat the same thing? I'm not an oil expert but I don't believe oil magically wears out just by sitting in a crankcase for a year? Is there some reason I'm not seeing as to why I need to drain and toss out 9 quarts of essentially brand-new LiquiMoly, just because it has hit it's first birthday?

On a related note 2 weeks ago I sold my first car, which had a built motor and had been sitting in my grandmother's barn in Georgia since 2007. The buyer said when he drained the oil it still looked brand new (No surprise, it was sealed inside a motor). If it didn't change in 14 years what's with this obsession with changing oil in 997's based on age rather than actual condition of the oil?

 

That's a great question that I always ask myself. On my 997.1 Turbo, I run Motul 300V 5W40. Great race oil with all the standard detergent packs but not designed to be used over 3000 miles. Like you, my car is on the road 6 months out of the year, and the past 5 years, I've put less than 1000 miles annually on the car but again, I still change my oil yearly. I wish I didn't have to.

I was told that the detergents in oil breakdown over time once it is exposed to air. Motul says the shelf life of their 300V is only 2 years. I too am looking for some good solid facts that oil is OK sitting sealed in a crankcase. I do remember that Porsche originally stated our cars need the oil changed every 2 year or 20,000 miles.

 

Interesting info, I will have to dig further on the shelf life rating for the LM oil I'm using. I hadn't thought about the potential detergent breakdown. While I wouldn't leave the oil in my car for 10 years if that's how long it took to hit 3,000 miles, I would feel a lot less guilty tossing 2 year old oil than one year old oil. I can probably get 2,000 hard miles on it in 2 years.

 

The problem is what happens to the various ingredients in the oil, as they tend to break down over time as much as mileage. Looking at your oil manufacturer's information will help you determine your answer, but in general, what I I have read, is that 1 year is a recommended max interval.

Ed

 

I have one data point that I am a bit ashamed and embarrassed to admit. I have multiple air cooled Porsche’s. I use Brad Penn 20-50w semi synthetic oil in them. I don’t drive them much, probably 300 miles per year. I check the oil every time I drive them and the oil always looks clean. I went 48 months- 4 years- and sent samples of 2 of my cars to Blackstone for oil analysis. Both came back perfect. EVERY parameter was well with spec including viscosity, TBN, water%, insolubles, etc. So based on Blackstone’s analysis of my 4 year old oil, apparently you can go longer than 1 year. Significantly longer in my case.

I am not advocating that you should go longer than the manufacturer’s recommendation, and in fact I change my 997tt oil religiously every 3500 miles because I drive it daily.

Again, this is only 1 data point of 2 samples from 2 cars. I’m in central CA, the weather here is very hot in the summer and pretty mild in the winter. The cars are stored indoors in my non-climate controlled shop building.

 

Good info! Thanks for posting.

I do remember when I followed the initial 2 year oil change when the car was still fairly new, that by 18 months, sludge had formed in the oil cap. Car had 10,000 miles of use in those 18 months running factory fill Mobil 1 0W40.

I changed my oil yearly after that.

 

I put this oil in last July. Plan is to leave it in until this coming October when I put the car away for winter and I'll send some of it off to be analyzed at that point. If it looks great I may go to a schedule of changing every other October unless I somehow hit 3000 miles in a single year (unlikely)

 

There’s a guy on rennlist that is looking at buying a 12,000 mile 996 x50 car that the owner didn’t change the oil for the first 16 years of ownership. Wonder how that oil would stack up with all starting and idling for all those years?

 

Yikes!

 

Its nice to get under the car once a year and have a peek at things with a quick oil change - I'm sure there is a science behind the oil breakdown and water / condensation if not fully warmed up, but its nice piece of mind regardless.

 

Oil will absorb moisture.....annual oil change in the grand scheme of things is cheap insurance...

 

If you really want to know how often you need to change your oil, change it after a year and send in the sample for analysis with blackstone labs. They can tell you for certain whether it could go longer, or was due for a change.

 

I have been considering moving to two year intervals. My car only gets driven a couple hundred miles a year. Seems like such a waste.