Thats interesting Eugene. Never thought of it this way. I've always kept mine near max and never below half way to minimum. I've never seen white smoke or an increase in oil burn. In fact my car burns relatively little oil. Before my last oil change I added only half a quart during the 4k miles I ran it. Guess I didn't need to add any at all.

Ari, if you decide to change oil after, get an oil analysis done to see how good your oil was and share it with us. Will be good for piece of mind for you and the rest of us going forward in regard to this situation especially for those of us that suggested change before.

 

Hey Eric! It was the chief foreman (well known in the local Porsche community) from the Livermore Porsche told us at one of his techtalks.

 

In the above case I'd change the oil before going to the track. The oil has 5K miles of city/street driving which mainly means contamination with water and unburned fuel. This lowers the oil's viscosity and it won't protect as good when it gets hot.

If the oil was fresh then you could get by changing it after the track.

I do not track my Porsches but when I did auto-x I was always told by those that did it often, many who worked as professional mechanics and some who built engines, that tracking a car requires additional servicing.

The person who thinks he can drive his car on the street for 5K miles then go to the track on that oil without changing it first is playing with fire.

Sincerely,

Macster.

 

Amazing breadth of responses and truly on two opposite sides of the spectrum. I'm going to do the track day on 5K miles of synthetic (good for 15K miles per Porsche) and take whoever's advice it was to send the used oil in for an analysis. I will then post the results. Should be rather definitive and prove the point one way or the other.

BTW my personal opinion mirrors the guy who said that 3-5 20 minute sessions are rather mild for a high performance driver's event.

For an added margin of safety, I always run 100 octane gas on a 91 octane tune at driver's events.

 

ARI, don't worry man, 3 or 5 20 minute sessions aren't putting you at risk. I will however say that I don't care what Porsche says, I wouldn't wait anywhere near 15k miles to change my oil on a performance car, especially one with performance modifications and that's driven hard. That is WAY too long.

Do the event, change your oil. And as long as you are doing events, change that oil in smaller intervals, especially the more events you do and the hotter it is outside.

 

I'll be very interested in hearing the result. A truly definitive test would be to sample and analyze the oil before and after the track event. Then you'd know the effect of 5K of street driving and the track event separately. Just a thought -- I have no idea how easy or costly that would be.

As an aside, I agree with folks who say 15K seems long (since I also change my oil sooner). But I'm wondering what's the logic behind our belief here. Why would the manufacturer recommend a longer interval than it should be? Seems like their incentive would be for the opposite.

 

+1... exactly what I'm thinking too.

 

If the track sessions are mild why go the expense and effort to visit the track in the first place?

Most of the time -- for in your case 20 minutes or so -- the engine is being used at or very near its peak output and at high revs.

This subjects the engine to high heat loads, high stress and this is the time you want the oil to be as good as it can be.

At other times, too, actually. There is no time when a critical fluid like oil is not critical to the continued health of the engine.

Running 100 octane is a bit overkill but better to err on the side of caution. I'd rather see the engine fed gasoline a few octane points too high than too low under track conditions.

Sincerely,

Macster.

 

My cars runs 1.3BAR of boost on the "low octane" 91 octane setting and has been dyno tuned. The higher octane gives me some peace of mind on the track.

We'll see the results of the oil debate soon.

 

A tune can change everything. The tune may dial back the timing so even though the boost is higher and the effective compression ratio is higher, the engine is less prone to enter the detonation danger zone.

I'm not sure I like this though -- I mean I like the fact the engine is kept out of the detonation danger zone (it wouldn't last long if it wasn't) -- but what I don't like about this is while the delayed (retarded) spark lowers the pressure developed in the combustion chamber also raises exhaust gas temps. In a turbo they run pretty warm already so... But that's the trade off I guess for wringing more HP.

Another trick is to enrichen the mixture some. A richer mixture, one richer than the typical 14.7:1 these cars normally run at (because this is the best air fuel ratio for the converters), is less likely to detonate and the engine runs a bit cooler too boot.

Even the stock engine controller is allowed to enrichen the mixture some when the driver makes a big torque demand in order to satisfy this torque demand In this situation the engine controller can temporarily suspend emissions compliance monitoring and just feed the engine more fuel. But these events are short-lived lasting only as long as the driver's foot is mashed down. One can tell when his is happening (the fuel is being enriched that is not what the driver's foot is doing) by using an OBD2 code reader/data viewer and noting when the emissions systems switch from closed loop mode (where they spend the majority of their time) to open loop mode.

Sincerely,

Macster.

 

I've never owned a car that "normally" ran at 14.7:1, AKA the stoichiometry of pure gasoline. That's way too lean, IMHO. Have you datalogged your vehicle and observed this result while under load?

 

I have a very mild setup from a conservative tuner compared to others. These are great cars and tough engines. The factory runs 1.6 bar of boost through a much more restrictive exhaust in a similar engine installed in the GT2RS and charges $250K for it... I'm not worried at all

BTW If I could spend $250K on a GT2 RS:

1. I Probably would
2. I would really consider a McLaren (that car is full of carbon fiber and has an 8,000 RPM twin turbo V8!!) Just an absolute steal compared to the last one @ $1,000,000