Oil Consumption query after taking 997S to a trackday

[knightrider]

Hey Guys

I took my car to Mallory Park on Saturday for a car show event/trackday. I took my car onto the track for one 15 minute session during which I pushed it quite hard (but not too hard due to large number of boy racer type cars on the same session plus my unfamiliarity with the circuit.

Anyhow, by the end of the 15 minute session my engine oil temp had hit 110 - 115 degrees (water temp was 80 degrees). After the session once I got home I checked the oil level and the car had used 1 segment of oil (400ml) during the session. I topped the oil up last weekend so I know it has definitely dropped at least 1 segment. I just wanted to ask is this kind of consumption normal or excessive for such a short track session?

On a side note, my tyre performance was very poor after a few laps - the car suddenly became very wallowly and it felt like I was driving on soft squishy tyres. My rears are near the limit and the fronts have 3 mm left (Pirelli Rosso's) - is it a myth that tyres with low tread should perform better (like slicks in warm weather) or is the reality that the rubber loses its quality towards the end of the tyre's life cycle? Certainly in my case I would suggest the latter is true!

 

[garyw]

I'd guess being as the oil measurement is segmented, a little bit of oil used or slightly different angle of the car could possibly cause it to show drop of a segment.

Nice way to finish off a set of tyre if they were that low []
Less rubber to disperse the heat and tyre pressure temps could of been the issue, but I'll let the more accomplished trackday guys answer it fully...

garyw

 

[Lancerlot]

Engine oil absorbs moisture and fluids in normal use. When it gets extra hot, this evaporates and reduces volume.

Also, higher engine revs will burn oil at a faster rate, but less than a litre usage on a track day should not give cause for concern.

Regards,

Clive.

 

[spyderman]

I've had 18" Rosso N4s on my Boxster over that last 13000 miles and four half track days and I've been extremely impressed with their grip and how they've lastest on track, especially compared with Michelin Pilot Sports on other Boxsters, which appeared to go off much faster. I've just replaced them with a set of the same. I was at Brands last Tuesday and I think did 6 sessions of 6 to 8 laps - not once did I feel the tyres going off. I was careful to monitor the pressures, though, and ran them nearer to the standard 29/36 as I'd run them too high at Bedford and worn off most of the tread pattern in the middle!

What size are you running? I guess 19"? I would think that having less sidewall and therefore less flex would have an impact of wear and longevity. If you're going to do a lot of track work, for better grip and lower cost, easier to source tyres, you might consider a set of 18" wheels.

 

[tscaptain]

I would first ask what is the "normal" consumption for your car. My last C2S used about 1lt/1500 miles (which increased if there was a track day!) As Gary says it could be that the level was just enough to take it into the full section and a little oil burn on track and elsewhere might have been enough to drop it one segment. It need not have used 400ml? The oil temps you had on track are quite normal.
Normal road tyres do lose grip as they near the end of their life and I do not think nearly bald road tyres make good slicks! I guess the reasoning that they do comes from the fact there is more rubber in contact with the surface. In fact Chris at Center Gravity recommends that the tyres are replaced when they get down to 3mm. This, as I recall, is something to do with the different types of rubber compound used in the tyre construction.
Tyre pressure may also have been an issue. It is normal to run slightly lower pressures on track and of course with spirited use the tyre pressures will increase anyway. The whole business of getting pressures and geometry right for use on track is very interesting. See this article about using a pyrometer
http://www.theracersgroup.com/news/show.php?id=372
That said I think it could be that your tyres are getting close to the end of their useful life and it is possible that caused the feeling of "soft squishy" tyres.

 

[okellyt]

ORIGINAL: tscaptain


That said I think it could be that your tyres are getting close to the end of their useful life and it is possible that caused the feeling of "soft squishy" tyres.

As can over inflated tyres - tyre pressures go up dramqtically under heavy use and a hot day, messign with the integrity of the tyre side wall and causing it to go "wobbly". If you haven't let some air out so it was under pressure before you started or monitored your tyre pressure during use this can happen.

 

[knightrider]

Hey I had the tyre pressures set at 37 front and 41 rears and as I only went out for 1 session I did not adjust them - were my pressures OK?

After I stopped the near side tyres had taken quite a beating and had loads of rubber 'blots' built up on them and all 4 tyres looked quite rough and scrubbed.

As I side note since my car had its Major Service done in Feb (during which the RMS and IMS seals were replaced under warranty) I have noticed the car is using a lot more oil. Consumption has gone from 1litre/3000miles to approx 1litre/1000miles since the service - is there any recourse to get the OPC to look at it as the car is now out of warranty?

 

[Rodney Naghar]

After 6 minutes round a track my tyre pressures can go up up over 15-20psi let alone the 15 hard minutes that you did. Not letting the air out would almost certainly have caused your car to behave like that.

 

[tscaptain]

ORIGINAL: knightrider

Hey I had the tyre pressures set at 37 front and 41 rears and as I only went out for 1 session I did not adjust them - were my pressures OK?

Consumption has gone from 1litre/3000miles to approx 1litre/1000miles since the service - is there any recourse to get the OPC to look at it as the car is now out of warranty?

If they were 37/41 before you went out they were probably around 45/50 by the end of the session! On a full track day I normally drop the pressures around 5psi before the first session and then check them as soon as I come in. At the end of the day when everything has cooled down I need to put in around 10psi to bring them back up for the drive home!
Regards the oil - probably not as I think 1lt/1000 is within the "normal" consumption limits.

 

[Lancerlot]

ORIGINAL: knightrider
As I side note since my car had its Major Service done in Feb (during which the RMS and IMS seals were replaced under warranty) I have noticed the car is using a lot more oil. Consumption has gone from 1litre/3000miles to approx 1litre/1000miles since the service - is there any recourse to get the OPC to look at it as the car is now out of warranty?

Nothing there to increase oil consumption - but get your OPC to check for leaks.

ORIGINAL: tscaptain
If they were 37/41 before you went out they were probably around 45/50 by the end of the session! On a full track day I normally drop the pressures around 5psi before the first session and then check them as soon as I come in. At the end of the day when everything has cooled down I need to put in around 10psi to bring them back up for the drive home!
Regards the oil - probably not as I think 1lt/1000 is within the "normal" consumption limits.

N2 anyone? [8|]

Regards,

Clive.