Oil burning/Engine life
03-20-2010, 01:51 PM
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Oil burning/Engine life
Does anyone know if the amount of oil burning has any correlation with the with how long the engine will last? My CS2 has about 5k miles and is using 1 quart per 1k miles. I know that Porsche considers this normal, but why do some cars burn no oil and others quite a bit?
03-20-2010, 03:14 PM
#3
Poseur
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We had this same discussion on and off since the 997 came out--both 997.1 and 997.2
It comes down to the 'luck of the draw' whether your engine will use oil or not. When they use oil, they use what I consider to be a lot--I think 1 quart every thousand miles is a lot. Others barely put any oil in their engines between oil changes. They measure it in ozs!
We did a poll/survey sometime back (perhaps you can find it in a search) that showed the vast number of 997 engines use little to no oil, but there is a 10-15% figure that use oil.
We've concluded that if Porsche knew what was causing it they would fix it. They haven't. Ditto on the 997.2 engines--and the trend may be toward more oil usage on the DI engines. (That's my subjective observation).
Someone posed this question in Automobile Magazine about a year ago and their experts concluded that it could be the results of the tolerance "stack." In short, if every component that affects oil consumption is on the edge of it's tolerance window, the additive effect could be excessive oil usage. They count on engine tolerances varying but not having every part on the edge--thus adding up to the worse oil burning situation ever possible.
I had my engine borescoped sometime back and they claim that they found nothing. But let's recall what drives oil burning (and we say burning because we NEVER see oil leaking or seeping anywhere). Oil can be consumed in these quantities either along the valve guides or within the pistons when the scrapper rings are not scrapping enough of the oil off the walls of the cylinder before the flash fire of the ignition burns the oil layer off.
Getting back to your original question--is engine life affected? Possibly. If an engine of today's design with a goal of reducing emissions continues to burn and burn oil excessively, it may ultimately be filling the cats up with soot. Since the emissions equipment on these cars carry a longer warranty (as mandated by law) than that on the vehicles (4/50K) then ultimately Porsche may wind up footing the bill for replacing a bunch of clogged cats. Only time will tell.
I have wanted to insert a hydrocarbons measuring probe into the engine BEFORE the cats to see just how high things are getting in there, but haven't pursued it with my dealership.
Again, it's the luck of the draw. I can't tell you how many people I know who have had Porsche engines (modern day ones) which have used oil excessively, to engines that use little to no oil. That tells me that the STYLE of driving has absolutely nothing to do with it. It's a mechanical issue that Porsche has, to date, been unable to sort out. So long as they can issue a TSB that says 1.6 quarts of oil every 620 miles is "within the acceptable range of consumption" and we buy off on it, there is no need to go further--in their mind.
It comes down to the 'luck of the draw' whether your engine will use oil or not. When they use oil, they use what I consider to be a lot--I think 1 quart every thousand miles is a lot. Others barely put any oil in their engines between oil changes. They measure it in ozs!
We did a poll/survey sometime back (perhaps you can find it in a search) that showed the vast number of 997 engines use little to no oil, but there is a 10-15% figure that use oil.
We've concluded that if Porsche knew what was causing it they would fix it. They haven't. Ditto on the 997.2 engines--and the trend may be toward more oil usage on the DI engines. (That's my subjective observation).
Someone posed this question in Automobile Magazine about a year ago and their experts concluded that it could be the results of the tolerance "stack." In short, if every component that affects oil consumption is on the edge of it's tolerance window, the additive effect could be excessive oil usage. They count on engine tolerances varying but not having every part on the edge--thus adding up to the worse oil burning situation ever possible.
I had my engine borescoped sometime back and they claim that they found nothing. But let's recall what drives oil burning (and we say burning because we NEVER see oil leaking or seeping anywhere). Oil can be consumed in these quantities either along the valve guides or within the pistons when the scrapper rings are not scrapping enough of the oil off the walls of the cylinder before the flash fire of the ignition burns the oil layer off.
Getting back to your original question--is engine life affected? Possibly. If an engine of today's design with a goal of reducing emissions continues to burn and burn oil excessively, it may ultimately be filling the cats up with soot. Since the emissions equipment on these cars carry a longer warranty (as mandated by law) than that on the vehicles (4/50K) then ultimately Porsche may wind up footing the bill for replacing a bunch of clogged cats. Only time will tell.
I have wanted to insert a hydrocarbons measuring probe into the engine BEFORE the cats to see just how high things are getting in there, but haven't pursued it with my dealership.
Again, it's the luck of the draw. I can't tell you how many people I know who have had Porsche engines (modern day ones) which have used oil excessively, to engines that use little to no oil. That tells me that the STYLE of driving has absolutely nothing to do with it. It's a mechanical issue that Porsche has, to date, been unable to sort out. So long as they can issue a TSB that says 1.6 quarts of oil every 620 miles is "within the acceptable range of consumption" and we buy off on it, there is no need to go further--in their mind.
03-20-2010, 05:22 PM
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We had this same discussion on and off since the 997 came out--both 997.1 and 997.2
It comes down to the 'luck of the draw' whether your engine will use oil or not. When they use oil, they use what I consider to be a lot--I think 1 quart every thousand miles is a lot. Others barely put any oil in their engines between oil changes. They measure it in ozs!
We did a poll/survey sometime back (perhaps you can find it in a search) that showed the vast number of 997 engines use little to no oil, but there is a 10-15% figure that use oil.
We've concluded that if Porsche knew what was causing it they would fix it. They haven't. Ditto on the 997.2 engines--and the trend may be toward more oil usage on the DI engines. (That's my subjective observation).
Someone posed this question in Automobile Magazine about a year ago and their experts concluded that it could be the results of the tolerance "stack." In short, if every component that affects oil consumption is on the edge of it's tolerance window, the additive effect could be excessive oil usage. They count on engine tolerances varying but not having every part on the edge--thus adding up to the worse oil burning situation ever possible.
I had my engine borescoped sometime back and they claim that they found nothing. But let's recall what drives oil burning (and we say burning because we NEVER see oil leaking or seeping anywhere). Oil can be consumed in these quantities either along the valve guides or within the pistons when the scrapper rings are not scrapping enough of the oil off the walls of the cylinder before the flash fire of the ignition burns the oil layer off.
Getting back to your original question--is engine life affected? Possibly. If an engine of today's design with a goal of reducing emissions continues to burn and burn oil excessively, it may ultimately be filling the cats up with soot. Since the emissions equipment on these cars carry a longer warranty (as mandated by law) than that on the vehicles (4/50K) then ultimately Porsche may wind up footing the bill for replacing a bunch of clogged cats. Only time will tell.
I have wanted to insert a hydrocarbons measuring probe into the engine BEFORE the cats to see just how high things are getting in there, but haven't pursued it with my dealership.
Again, it's the luck of the draw. I can't tell you how many people I know who have had Porsche engines (modern day ones) which have used oil excessively, to engines that use little to no oil. That tells me that the STYLE of driving has absolutely nothing to do with it. It's a mechanical issue that Porsche has, to date, been unable to sort out. So long as they can issue a TSB that says 1.6 quarts of oil every 620 miles is "within the acceptable range of consumption" and we buy off on it, there is no need to go further--in their mind.
It comes down to the 'luck of the draw' whether your engine will use oil or not. When they use oil, they use what I consider to be a lot--I think 1 quart every thousand miles is a lot. Others barely put any oil in their engines between oil changes. They measure it in ozs!
We did a poll/survey sometime back (perhaps you can find it in a search) that showed the vast number of 997 engines use little to no oil, but there is a 10-15% figure that use oil.
We've concluded that if Porsche knew what was causing it they would fix it. They haven't. Ditto on the 997.2 engines--and the trend may be toward more oil usage on the DI engines. (That's my subjective observation).
Someone posed this question in Automobile Magazine about a year ago and their experts concluded that it could be the results of the tolerance "stack." In short, if every component that affects oil consumption is on the edge of it's tolerance window, the additive effect could be excessive oil usage. They count on engine tolerances varying but not having every part on the edge--thus adding up to the worse oil burning situation ever possible.
I had my engine borescoped sometime back and they claim that they found nothing. But let's recall what drives oil burning (and we say burning because we NEVER see oil leaking or seeping anywhere). Oil can be consumed in these quantities either along the valve guides or within the pistons when the scrapper rings are not scrapping enough of the oil off the walls of the cylinder before the flash fire of the ignition burns the oil layer off.
Getting back to your original question--is engine life affected? Possibly. If an engine of today's design with a goal of reducing emissions continues to burn and burn oil excessively, it may ultimately be filling the cats up with soot. Since the emissions equipment on these cars carry a longer warranty (as mandated by law) than that on the vehicles (4/50K) then ultimately Porsche may wind up footing the bill for replacing a bunch of clogged cats. Only time will tell.
I have wanted to insert a hydrocarbons measuring probe into the engine BEFORE the cats to see just how high things are getting in there, but haven't pursued it with my dealership.
Again, it's the luck of the draw. I can't tell you how many people I know who have had Porsche engines (modern day ones) which have used oil excessively, to engines that use little to no oil. That tells me that the STYLE of driving has absolutely nothing to do with it. It's a mechanical issue that Porsche has, to date, been unable to sort out. So long as they can issue a TSB that says 1.6 quarts of oil every 620 miles is "within the acceptable range of consumption" and we buy off on it, there is no need to go further--in their mind.
Dan,
Thanks for your informative response. I appreciate you taking the time.
Jared
03-20-2010, 05:25 PM
#5
Poseur
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Here's that old poll--done when the 997.1 was being polled. The 997.2 was not out yet.
https://rennlist.com/forums/997-foru...sage-poll.html
https://rennlist.com/forums/997-foru...sage-poll.html
03-20-2010, 08:03 PM
#6
Race Director
Does anyone know if the amount of oil burning has any correlation with the with how long the engine will last? My CS2 has about 5k miles and is using 1 quart per 1k miles. I know that Porsche considers this normal, but why do some cars burn no oil and others quite a bit?
I can't add much to the other posts. Tolerance stacking is as good an explanation as any. Now this doesn't mean necessarily larger clearances or sloppy piston/cylinder fits, but more subtle tolerances like the force an oil scraper ring has against the cylinder wall, how tightly or loosely the valve stem seals seal the valve stems. It can even be related to variations in how well or not the AOS removes oil vapor from the crankcase fumes before the fumes are routed to the intake and burned in the engine.
You might consider running the oil level a bit lower, say a bar or two lower than the max or down a bar or two lower than where you currently run the oil. Do not run the oil so low it is right at the minimum level line though. Allow at least a couple of bars of oil.
If the oil's original you might consider changing it. A new engine tends to load up its oil with water vapor and unburned fuel both of which make the oil less viscous and more prone to making its way past rings, seals or contributing more oil to the crankcase vapors.
How you drive the car plays a role. Avoid excessive engine idling and high rpm engine speeds.
As for what engine oil consumption portends for engine longevity as long as the engine runs well otherwise, delivers reasonable gas mileage, and exhibits no other odd or troublesome behavior the engine should last as long as you want it to.
The best thing you can do is change the oil/filter regularly -- and I suggest more often then the owners manual calls for.
I change my Porsches' oil/filter every 5K miles and have over 229K miles on my 02 Boxster and have put nearly 20K miles on my 03 Turbo since June last year when I bought it used with 9500 miles.
The Boxster has started using a bit of oil, nearly a quart in 5K miles. I don't drive it quite like I used to, using it a bit more for short trips than I used to. Also, it spends more time idling and I believe it or not believe I'm pushing the engine harder now than I used to, so it still sees high rpm usage though not prolonged of course.
Sincerely,
Macster.
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03-22-2010, 11:21 AM
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03-22-2010, 12:24 PM
#10
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dealers thinks its absurd. But its on the cusp of being in the guideline for Porsche. They back my frustration. At one point it was a visit to them every two fill ups becuase the damn oil light came on.
They gave me a case of oil so i can top it off myself. So far I have had to use a quart in the last week. My oil level was BELOW the safe level and I had just gotten topped off two weeks ago.
We decided I did not need an oilchange at 10,000 miles because i essentially added 14 quarts durign the first 9500 miles!
Porsche basically built an oil consuming engine that never needs oil changes. it simply cosumes so much oil, you are always adding.
They gave me a case of oil so i can top it off myself. So far I have had to use a quart in the last week. My oil level was BELOW the safe level and I had just gotten topped off two weeks ago.
We decided I did not need an oilchange at 10,000 miles because i essentially added 14 quarts durign the first 9500 miles!
Porsche basically built an oil consuming engine that never needs oil changes. it simply cosumes so much oil, you are always adding.
03-22-2010, 01:02 PM
#12
I think the oil consumption does not have anything to do with the fact that these are DI engines. The new DI engines use a different process to form the inner surface of the cylinder. I believe this is where the problem comes from regarding oil consumption. My BMW 535 has DI but with cast iron cylinder liners there is no real oil consumption after break-in. likewise, my 2008 C2S ( littel or no oil consumption after break-in) has the special coating applied to inside surface of the cylinders rather than the newer aluminum compound that is etched on the DI engines. Perhaps the newer process is not as consistent?
03-22-2010, 09:26 PM
#14
Race Director
dealers thinks its absurd. But its on the cusp of being in the guideline for Porsche. They back my frustration. At one point it was a visit to them every two fill ups becuase the damn oil light came on.
They gave me a case of oil so i can top it off myself. So far I have had to use a quart in the last week. My oil level was BELOW the safe level and I had just gotten topped off two weeks ago.
We decided I did not need an oilchange at 10,000 miles because i essentially added 14 quarts durign the first 9500 miles!
Porsche basically built an oil consuming engine that never needs oil changes. it simply cosumes so much oil, you are always adding.
They gave me a case of oil so i can top it off myself. So far I have had to use a quart in the last week. My oil level was BELOW the safe level and I had just gotten topped off two weeks ago.
We decided I did not need an oilchange at 10,000 miles because i essentially added 14 quarts durign the first 9500 miles!
Porsche basically built an oil consuming engine that never needs oil changes. it simply cosumes so much oil, you are always adding.
The combustion by-products are building up and a draining of the oil is the only way to remove them.
The dealer was just afraid of pouring gasoline on your oil consumption fire.
The engine might not or it might improve its oil consumption but it won't make matters any better to skip regular oil/filter services. In fact with an oil change consumption might go down cause the old oil is so full of water/unburned fuel is it quite fluid and more likely to make it past the rings, teh valve stems seals, even make it past the AOS as oil vapor cause the oil gets frothy as the anti-foaming additive package is depleted.
Sincerely,
Macster.
03-22-2010, 10:49 PM
#15
Three Wheelin'
We had this same discussion on and off since the 997 came out--both 997.1 and 997.2
Getting back to your original question--is engine life affected? Possibly. If an engine of today's design with a goal of reducing emissions continues to burn and burn oil excessively, it may ultimately be filling the cats up with soot. Since the emissions equipment on these cars carry a longer warranty (as mandated by law) than that on the vehicles (4/50K) then ultimately Porsche may wind up footing the bill for replacing a bunch of clogged cats. Only time will tell.
Getting back to your original question--is engine life affected? Possibly. If an engine of today's design with a goal of reducing emissions continues to burn and burn oil excessively, it may ultimately be filling the cats up with soot. Since the emissions equipment on these cars carry a longer warranty (as mandated by law) than that on the vehicles (4/50K) then ultimately Porsche may wind up footing the bill for replacing a bunch of clogged cats. Only time will tell.