996.2 cold start smoke
#31
Rennlist Member
10w/60 is much used en Europe and infact one of Germany’s best Porsche engine rebuilder Pomotec https://www.pomotec.de/ uses and recommends only Motul v300 Completion 15w/50 all year around
#32
Rennlist Member
Maybe he rebuilds more engines by recommending 15w?
#35
Hartech also recommends running 10w50 when mileage starts increasing. In warmer climates it is certainly not a problem. Even less if you track your car. Even Mobil has a nice alternative with their 5w50 oil.
Most of these higher viscosity oils also contain a bit different additive package. And don’t be fooled. The 300V double ester and equivalents do flow almost as good as the lower grades when cold. So at cold startup oil pressure build up and oil delivery to the engine internals is almost the same. So nothing to worry on the supply and wear side so much. The film formation and other characteristics however a different.
Back on topic, my puff of smoke, did not go away when changing oil viscosities. I have tried a variety of oils from 0w40 or 5w40 in winter and 10w50 for summer and occasionally track day.
Oil consumption of around 1 quart per 2000-2500 miles stayed the same over my previous 45k miles of ownership independent of oil viscosity used. Curious how it goes now all injectors have been cleaned and checked.
Most of these higher viscosity oils also contain a bit different additive package. And don’t be fooled. The 300V double ester and equivalents do flow almost as good as the lower grades when cold. So at cold startup oil pressure build up and oil delivery to the engine internals is almost the same. So nothing to worry on the supply and wear side so much. The film formation and other characteristics however a different.
Back on topic, my puff of smoke, did not go away when changing oil viscosities. I have tried a variety of oils from 0w40 or 5w40 in winter and 10w50 for summer and occasionally track day.
Oil consumption of around 1 quart per 2000-2500 miles stayed the same over my previous 45k miles of ownership independent of oil viscosity used. Curious how it goes now all injectors have been cleaned and checked.
Last edited by Silk; 10-28-2018 at 06:58 AM.
#36
Rennlist Member
^^ Agree, except 300v looks about the same viscosity as 15w. It’s the viscosity rating at cold temps that matters (for cold starts).
For example:
• Mobil 1 0w-40
○ Viscosity at 40C = 70.8
○ Viscosity at 100C = 12.9
○ Viscosity Index = 186
○ Flash point 226C
○ Density = 0.8456
○ Pour Point = -54C
• Mobil 1 15w-50
○ Viscosity at 40C = 125
○ Viscosity at 100C = 18
○ Viscosity Index = 160
○ Flash point 232C
○ Density = 0.87
○ Pour Point = -39C
• Mobil 1 5w-50
○ Viscosity at 40C = 104.3
○ Viscosity at 100C = 17.1
○ Viscosity Index = 179
○ Flash point 232C
○ Density = 0.8499
○ Pour Point = -42C
Notice that viscosity at 40C for 0w is 71 versus 125 for 15w Mobil 1 vs Mobil 1. This 15w oil won’t even pour if it’s -38F outside!
What is 300v 40C viscosity? About the same as Mobil 15w:
Viscosity grade: SAE J 300 / SAE15W-50
Density at 20°C (59°F): ASTM D1298 / 0.868
Viscosity at 40°C (104°F): ASTM D445 / 122.9 mm²/s
Viscosity at 100°C (212°F): ASTM D445 / 18.1 mm²/s
HTHS viscosity at 150°C (302°F): ASTM D4741 / 5.3 mPa.s
Viscosity index: ASTM D2270 / 164
Pour point: ASTM D97 -39°C / -38.2°F
Flash point: ASTM D92 238°C / 460.4°F
TBN: ASTM D2896 / 8.25 mg KOH/g
All this said, it probably has almost nothing to do with smoke at cold start, Lol!
For example:
• Mobil 1 0w-40
○ Viscosity at 40C = 70.8
○ Viscosity at 100C = 12.9
○ Viscosity Index = 186
○ Flash point 226C
○ Density = 0.8456
○ Pour Point = -54C
• Mobil 1 15w-50
○ Viscosity at 40C = 125
○ Viscosity at 100C = 18
○ Viscosity Index = 160
○ Flash point 232C
○ Density = 0.87
○ Pour Point = -39C
• Mobil 1 5w-50
○ Viscosity at 40C = 104.3
○ Viscosity at 100C = 17.1
○ Viscosity Index = 179
○ Flash point 232C
○ Density = 0.8499
○ Pour Point = -42C
Notice that viscosity at 40C for 0w is 71 versus 125 for 15w Mobil 1 vs Mobil 1. This 15w oil won’t even pour if it’s -38F outside!
What is 300v 40C viscosity? About the same as Mobil 15w:
Viscosity grade: SAE J 300 / SAE15W-50
Density at 20°C (59°F): ASTM D1298 / 0.868
Viscosity at 40°C (104°F): ASTM D445 / 122.9 mm²/s
Viscosity at 100°C (212°F): ASTM D445 / 18.1 mm²/s
HTHS viscosity at 150°C (302°F): ASTM D4741 / 5.3 mPa.s
Viscosity index: ASTM D2270 / 164
Pour point: ASTM D97 -39°C / -38.2°F
Flash point: ASTM D92 238°C / 460.4°F
TBN: ASTM D2896 / 8.25 mg KOH/g
All this said, it probably has almost nothing to do with smoke at cold start, Lol!
#37
1. no more degrading diaphragm in the AOS; constantly changing high vacuum, especially in high rpm coming of the throttle is what wears out the flexible diaphragm over time.
2. no more more oil and other dirt directly in the intake.
3. no risk for hydrolocking your engine in case too much oil gets past a not proper functioning AOS. Or in case the AOS gets overwhelmed by oil collecting in one of the heads for whatever reason. By rerouting the AOS it stays always open and functions as a normal catch tank, one with a oil retour to the oil pan.
4. cooler air in the intake, rerouting makes the crankcase fumes cool down more before they enter the engine again. makes for some noticeable extra bhp.
The biggest advantage is nr. 3 Protect your engine. At least It saved mine two months ago when the scavenge pump in cilinder head 1 started deteriorating. At some point oil was coming out not only at high speed right hand turns, but even at 30-40mph. As the AOS vent in head 1 got overwhelmed with oil, pressure went up in the crankcase and oil was literally pushed out of the AOS. If that would have gone directly in the intake it was game over. At some point with a fast right hand curve 150ml got dumped out of the engine via the AOS.
#38
Oli use the past 1500km is 0,5l but still the same smoke out of bank 2 exhaust. Clearing up after a few hundreds of meters driving. As long as I don’t let it idle.
Changed spark plugs the other day and they are all quite black. Dry carbon not oily. Mostly cyl 3, 5, and 6
Maybe running a little rich?
checked MAF but is looks fine and clean.
Had a camera in all cylinders but dit not find any nasty things.
Changed spark plugs the other day and they are all quite black. Dry carbon not oily. Mostly cyl 3, 5, and 6
Maybe running a little rich?
checked MAF but is looks fine and clean.
Had a camera in all cylinders but dit not find any nasty things.