Another GT4 Oil Report
#16
From your profile, I can't tell where you live, but you could always run 50:50 the Mobil 0W40 and 5W50 and then 100% the 5W50 for summer/track season. If you live in the artic, yes use 0W40. If you drive in the cold weather and keep the car in a garage, the 5W50 is just fine.
As it stands I am still a bit surprised at the temps that P seems to feel are within its normal operating range. Determination as to if I should consider a different oil/weight was one reason I was curious as to the results of this test. I do not think I will get back on track this year, so I will probably just have it swapped before starting next. Either way, will be interested in the result between the six days on the prior sample and the three on the current.
#17
Race Director
From your profile, I can't tell where you live, but you could always run 50:50 the Mobil 0W40 and 5W50 and then 100% the 5W50 for summer/track season. If you live in the artic, yes use 0W40. If you drive in the cold weather and keep the car in a garage, the 5W50 is just fine.
If ambient temperatures are high enough that one can run 5w-50 year 'round that's fine. I run it in both of my cars here in CA. (Was 101F the other day here and in a couple of days could again get nearly 100F. Stupid "fall" weather.)
But if ambient temperatures get too low -- the temperature Porsche offers is -25C (about -13F0 -- Porsche says to run 0w-40. Frankly to be "safe" I'd switch to 0w-40 at an even higher temperature.
Say if ambient temperatures were at or below 32F that's when I'd run 0w-40. Then when spring arrives and ambient temperatures are above 32F I'd switch back to 5w-50.
#18
Race Car
https://mobiloil.com/~/media/amer/us...guide-2016.pdf
Yes. Mobil 1 is fully compatible with conventional motor oils, semi-synthetic motor oils and other synthetic motor oils, should it be necessary to mix them. But the superior performance of Mobil 1 will be reduced by diluting it. (from M! website)
Yes. Mobil 1 is fully compatible with conventional motor oils, semi-synthetic motor oils and other synthetic motor oils, should it be necessary to mix them. But the superior performance of Mobil 1 will be reduced by diluting it. (from M! website)
#20
Banned
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And Kevin is; one of the most trusted tunners on Rennlist, has seen hundreds and hundreds of UOA's, and hundreds of these Porsche engines when taken apart.
You can safely blend Mobil 5W50 with Mobil 0W40.
#22
Three Wheelin'
Does anyone know where I can find the most recent approved list?
#23
Motul's website still shows approved A40
#25
Just make sure it is unleaded. I've heard stories about my local track's fuel farm and I will not buy gas there ever again. I now bring my race gas with me, purchased from a local distributor who keeps it in an above ground tank separate from the leaded race gas variants. I trust that far more than the track's fuel farm. I also get 100 octane unleaded at about $3.00 per gallon cheaper. No brainer for me.
As far as I know, unless the DME is tuned for the octane, the DME will not add timing, only retard if knocking is heard.
As far as I know, unless the DME is tuned for the octane, the DME will not add timing, only retard if knocking is heard.
#26
Rennlist Member
Just make sure it is unleaded. I've heard stories about my local track's fuel farm and I will not buy gas there ever again. I now bring my race gas with me, purchased from a local distributor who keeps it in an above ground tank separate from the leaded race gas variants. I trust that far more than the track's fuel farm. I also get 100 octane unleaded at about $3.00 per gallon cheaper. No brainer for me.
As far as I know, unless the DME is tuned for the octane, the DME will not add timing, only retard if knocking is heard.
As far as I know, unless the DME is tuned for the octane, the DME will not add timing, only retard if knocking is heard.
#27
Rennlist Member
My first oil report was identical to the OPs except zero lead.
#28
Rennlist Member
The last time I gassed up at VIR I almost put leaded in. I can't remember if that was 100 octane or what. I moved to another pump with higher octane than 93 (maybe 98) that said it was unleaded, and it was still $8/gallon. Maybe you got the wrong one by accident like I almost did or maybe the gas delivery guy put the wrong thing in the tanks before you were there.
I have not had the oil analyzed in mine (yet).
I have not had the oil analyzed in mine (yet).
#29
My indie shop's manager, who races at the same track as I do, told me that the track's fuel farm manager told him that the delivery trucks have put in leaded in the unleaded tanks and they could not guarantee that the fuel was lead free. The pump labeling didn't help. One pump has Sunocco Supreme sticker and unleaded stickers, which conflict, and the other has 360GTX sticker and leaded stickers. I can understand why the delivery trucks have issues.
My first cat meltdown occurred on the way back from the track after using their 'unleaded' race gas exclusively. Highway mileage dropped from 30+ to 23 MPG. The CELs started with the next drive. The Cat's ceramic cores were glossy black instead of grey or white.
I had the headers replaced in the off-season and the replacements started to fail after two DE weekends, but the cores still look light grey (but highway mileage was down to 26 MPG) I have been careful to avoid the track gas since then. The headers may recover now that the fuel mixture issue has been solved.
I had to diagnose the issues myself. The major cause was that the O2 sensors were causing the fuel to run really lean at low RPM and overly rich at high RPM under load. Not sure if the gas was the cause or I just got unlucky. During the debug phase, I went to catless headers to ensure I didn't ruin a third set of cats. The second issue was that the overheated mufflers had the steel wool packing vibrate and chip, creating a lot of metal dust that blocked flow by lodging in the ceramic wool packing. I dyno tested with an intentional leak before the mufflers and showed a 50HP gain up to 3500 RPM and a 20 HP gain at 6500 RPM versus no leak. So new mufflers went on, too. Unlikely to be random luck since both banks behaved similarly. An expensive lesson.
V6
My first cat meltdown occurred on the way back from the track after using their 'unleaded' race gas exclusively. Highway mileage dropped from 30+ to 23 MPG. The CELs started with the next drive. The Cat's ceramic cores were glossy black instead of grey or white.
I had the headers replaced in the off-season and the replacements started to fail after two DE weekends, but the cores still look light grey (but highway mileage was down to 26 MPG) I have been careful to avoid the track gas since then. The headers may recover now that the fuel mixture issue has been solved.
I had to diagnose the issues myself. The major cause was that the O2 sensors were causing the fuel to run really lean at low RPM and overly rich at high RPM under load. Not sure if the gas was the cause or I just got unlucky. During the debug phase, I went to catless headers to ensure I didn't ruin a third set of cats. The second issue was that the overheated mufflers had the steel wool packing vibrate and chip, creating a lot of metal dust that blocked flow by lodging in the ceramic wool packing. I dyno tested with an intentional leak before the mufflers and showed a 50HP gain up to 3500 RPM and a 20 HP gain at 6500 RPM versus no leak. So new mufflers went on, too. Unlikely to be random luck since both banks behaved similarly. An expensive lesson.
V6