High Mileage U.S. '86 Carrera Oil Consumption
06-19-2003, 01:30 AM
#1
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High Mileage U.S. '86 Carrera Oil Consumption
After owning a very neat bone stock '86 911 coupe for the past year I have a question about oil consumption on non-rebuilt 200,000 mile (and counting) 3.2 engines.
I'm not wanting to re-open the many threads that appear on the general oil consumption issue in both the active lists and archives but rather get a quick assessment on how I (or rather my well worn engine!) might be doing.
I'm fairly confident that I have all service records from about 5,000 miles on because I have a VERY thick file that has receipts for things that I feel unscrupulous sellers would selectively 'misplace' and not pass on or make available for examination prior to a sale.
Among other things, the receipts prove consistent oil changes at an approximate rate of every 2000 miles right up to when I made the purchase. Is this good or what?!?!
I also had a very positive "whole car" PPI performed by the local OPC, who passed on my approval to perform a compression and leak down test as, after road testing the car, they felt that it was unnecessary!?!?.
I've never driven an outright competition car but have owned several high performance ones and have had the recent experience of driving a 2002 Carrera at Road Atlanta during a 2 day PDE course.
What limited experience I have tells me that the car (for its mileage) is NOT appreciably down on HP or torque - it's quick like a bunny and can easily scare you if you don't keep focused.
With that said, at 200,000 miles on an apparently unrebuilt engine (neither top end or otherwise) I'm using 1 quart of Valvoline 20W/50 MaxLife approximately every 500 miles and am consistently getting MPG figures (city/highway combined) of 21 MPG.
I get a light blue smoke puff (that smells like burning oil) on about 1 out of every 7 start-ups that occur only after sitting overnight and have never seen (or smelled burning oil) smoke after the engine has been running for about 1 minute or is otherwise warm.
As a point of reference I do follow the popular rule of keeping the oil level around the halfway mark on the dipstick, so I shouldn’t be falling afoul of the "overfill" consensus.
I've also had my wife follow me on several occasions with instructions to look for smoke while I purposely varied my acceleration and deceleration with the throttle and the result has always been the same - no visible smoke.
I've found I can even improve the 1:7 cold startup smoke puff syndrome to 1:15 by just letting the car idle for a bit (like you're getting ready to check the oil level) BEFORE you shut the engine down for the night.
I'm not sure why this seems to work (for me). Perhaps it has to do with allowing the oil to recover to the tank at a lower pressure, and subsequently lowering the pressure in the entire oil system, as opposed to remaining at a higher pressure (hence making it easier for oil to leak past worn valve guides/piston rings, whatever) in the primary lubrication circuits until the pressure eventually dissipates. I'm certainly no automotive engineer and I sure would like to hear the gurus chime in on this theory.
One thing that I think needs mentioning (although I'm really getting off subject here) is that the engine IS of horizontal configuration. We don't have the advantage of a "V" configuration where excess oil (assisted by gravity) has the opportunity to drain OUT of the combustion chamber once the engine is stopped and put to rest for a while. In a flat (horizontal) configuration it seems to me that any excess oil would be limited in its ability to "drain" anywhere, and would be present at the next cold startup, giving us the "smoke puff" that many owners think means the engine is near death!
To FINALLY get back on subject, the RPM redline on this car is about 6300 as marked on the tachometer <or> 6520 as listed in my owners manual. In any case I limit myself to about 5900 and try to take it to that range when conditions permit - usually about 4 or 5 times a week. In doing so I utilize 2nd gear through 3rd in most cases and (when the conditions are exceptional) I sometimes continue on to 4th.
The end point would be that this older car, with an added year's worth of driving in the manner described above, has an unrebuilt stock 3.2 Motronic engine that appears to be no worse off for wear other than liking its oil. No weird noises, no rattles, no mysterious knocks or thumps - and it still easily runs to the point where it can quickly exceed my "need for speed!".
Should I count my blessings and schedule a rebuild or hang in there and go for 500,000 miles? You decide. I'd really like to hear some experienced and level thoughts on the matter!
Barry A. Waters
baw_86_carrera@yahoo.com
I'm not wanting to re-open the many threads that appear on the general oil consumption issue in both the active lists and archives but rather get a quick assessment on how I (or rather my well worn engine!) might be doing.
I'm fairly confident that I have all service records from about 5,000 miles on because I have a VERY thick file that has receipts for things that I feel unscrupulous sellers would selectively 'misplace' and not pass on or make available for examination prior to a sale.
Among other things, the receipts prove consistent oil changes at an approximate rate of every 2000 miles right up to when I made the purchase. Is this good or what?!?!
I also had a very positive "whole car" PPI performed by the local OPC, who passed on my approval to perform a compression and leak down test as, after road testing the car, they felt that it was unnecessary!?!?.
I've never driven an outright competition car but have owned several high performance ones and have had the recent experience of driving a 2002 Carrera at Road Atlanta during a 2 day PDE course.
What limited experience I have tells me that the car (for its mileage) is NOT appreciably down on HP or torque - it's quick like a bunny and can easily scare you if you don't keep focused.
With that said, at 200,000 miles on an apparently unrebuilt engine (neither top end or otherwise) I'm using 1 quart of Valvoline 20W/50 MaxLife approximately every 500 miles and am consistently getting MPG figures (city/highway combined) of 21 MPG.
I get a light blue smoke puff (that smells like burning oil) on about 1 out of every 7 start-ups that occur only after sitting overnight and have never seen (or smelled burning oil) smoke after the engine has been running for about 1 minute or is otherwise warm.
As a point of reference I do follow the popular rule of keeping the oil level around the halfway mark on the dipstick, so I shouldn’t be falling afoul of the "overfill" consensus.
I've also had my wife follow me on several occasions with instructions to look for smoke while I purposely varied my acceleration and deceleration with the throttle and the result has always been the same - no visible smoke.
I've found I can even improve the 1:7 cold startup smoke puff syndrome to 1:15 by just letting the car idle for a bit (like you're getting ready to check the oil level) BEFORE you shut the engine down for the night.
I'm not sure why this seems to work (for me). Perhaps it has to do with allowing the oil to recover to the tank at a lower pressure, and subsequently lowering the pressure in the entire oil system, as opposed to remaining at a higher pressure (hence making it easier for oil to leak past worn valve guides/piston rings, whatever) in the primary lubrication circuits until the pressure eventually dissipates. I'm certainly no automotive engineer and I sure would like to hear the gurus chime in on this theory.
One thing that I think needs mentioning (although I'm really getting off subject here) is that the engine IS of horizontal configuration. We don't have the advantage of a "V" configuration where excess oil (assisted by gravity) has the opportunity to drain OUT of the combustion chamber once the engine is stopped and put to rest for a while. In a flat (horizontal) configuration it seems to me that any excess oil would be limited in its ability to "drain" anywhere, and would be present at the next cold startup, giving us the "smoke puff" that many owners think means the engine is near death!
To FINALLY get back on subject, the RPM redline on this car is about 6300 as marked on the tachometer <or> 6520 as listed in my owners manual. In any case I limit myself to about 5900 and try to take it to that range when conditions permit - usually about 4 or 5 times a week. In doing so I utilize 2nd gear through 3rd in most cases and (when the conditions are exceptional) I sometimes continue on to 4th.
The end point would be that this older car, with an added year's worth of driving in the manner described above, has an unrebuilt stock 3.2 Motronic engine that appears to be no worse off for wear other than liking its oil. No weird noises, no rattles, no mysterious knocks or thumps - and it still easily runs to the point where it can quickly exceed my "need for speed!".
Should I count my blessings and schedule a rebuild or hang in there and go for 500,000 miles? You decide. I'd really like to hear some experienced and level thoughts on the matter!
Barry A. Waters
baw_86_carrera@yahoo.com
06-19-2003, 03:24 AM
#2
It's been said that mileage isn't really a good indicator of overall engine condition. That being noted, there are guys running around with well over 300K and still going strong.
My SC is exactly like yours by description I have about 217K on what appears to be an unopened motor. Even our oil consumption's the same but I have leaks- I asked the same question a year ago and was told just to drive it. When you foul plugs, or start going into the sub 400 mi / qt range then start thinking about it...Sounds like good advice to me.
rjp
My SC is exactly like yours by description I have about 217K on what appears to be an unopened motor. Even our oil consumption's the same but I have leaks- I asked the same question a year ago and was told just to drive it. When you foul plugs, or start going into the sub 400 mi / qt range then start thinking about it...Sounds like good advice to me.
rjp
06-19-2003, 03:37 AM
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I can just speak from my experience, 118K (high for most cars) and 1-2% leakage per cylinder on leak down test last Jan. I rarely have to add oil maybe 1 qt. between changes every 3,000 miles so a qt. every 1,500 miles.
Oil was changed religiously 3 - 5,000 miles by previous, older owners. There is never any blue smoke while driving but sometimes after start up there's a blue puff, especially if it's been sitting for a while. I've been told that's due to the gravity effect you mentioned on "flat" engines.
I never drive it hard until it is warm.
I could easily see going 200K and not needing a rebuild. You engine does not sound worn except for the oil consumption. A leak down test will show it the wear is in the valve area or rings.
My bet is valve area. Top end rebuild is relatively affordable. But then you have to ask yourself "as long as I'm doing that for $4,000 should I do the whole thing for another $4,000?".
Decisions, decisions. I'd keep driving it or maybe get the valves done.
Pete
86 Carrera Coupe
Oil was changed religiously 3 - 5,000 miles by previous, older owners. There is never any blue smoke while driving but sometimes after start up there's a blue puff, especially if it's been sitting for a while. I've been told that's due to the gravity effect you mentioned on "flat" engines.
I never drive it hard until it is warm.
I could easily see going 200K and not needing a rebuild. You engine does not sound worn except for the oil consumption. A leak down test will show it the wear is in the valve area or rings.
My bet is valve area. Top end rebuild is relatively affordable. But then you have to ask yourself "as long as I'm doing that for $4,000 should I do the whole thing for another $4,000?".
Decisions, decisions. I'd keep driving it or maybe get the valves done.
Pete
86 Carrera Coupe
06-19-2003, 10:58 AM
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301,5XX Mi. and counting! Glad to hear from some other high milage guys. I use about 1 QT evey 1000mi. I see blue smoke evey 5-7 start ups. This goes away fairly quickly. I never see smoke while driving (unless I do not let it idle and burn off for 30 sec to a min.). I follow the prior mentioned easy till warm rule. I do not go above 3000 till warm.
06-19-2003, 12:25 PM
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I have an 86 with 140k on it. I'm having a top end done now. My car smoked a bit at start up and not just morning start ups. Not all the time but more than I liked. Oil was 1 qt for 600 miles. At last tune up one cylinder was down on compression. Once the engine was opened it was one bad exhaust valve guide. It was letting oil into the cylinder. Everything else in the engine was great. I suppose I could have gone longer but I wanted to get a bit more power. C2s should help that. 
06-19-2003, 03:53 PM
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Barry - I see you are new here. A quick search would have given you the answer you want.
Per Porsche technical specifications:
"The standard figure for oil consumption for the 3.2L and 3.6L engines from the Porsche manuals is 1.5Litres/1000klms."
Converting this to miles per quart, you get about 1.6 quarts per 620 miles or 2.5 quarts per 1,000 miles. So, per Porsche, you are considered within normal operating specs until your oil consumption exceeds one quart per 400 miles.
By the way, my 87 Coupe with 115K on the odometer consumes 1 quart of oil anywhere from 600 - 1000 miles depending on city/highway driving or DE usage. Not one mechanic I have spoken to (and I speak to many) has had any concern about this.
Per Porsche technical specifications:
"The standard figure for oil consumption for the 3.2L and 3.6L engines from the Porsche manuals is 1.5Litres/1000klms."
Converting this to miles per quart, you get about 1.6 quarts per 620 miles or 2.5 quarts per 1,000 miles. So, per Porsche, you are considered within normal operating specs until your oil consumption exceeds one quart per 400 miles.
By the way, my 87 Coupe with 115K on the odometer consumes 1 quart of oil anywhere from 600 - 1000 miles depending on city/highway driving or DE usage. Not one mechanic I have spoken to (and I speak to many) has had any concern about this.
06-19-2003, 05:31 PM
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interesting - a thread about what's NOT wrong w/ the 911 motor (& how to keep it that way). wherever this leads, don't let swamp-chevy catch wind of it - it'll give him (& his fellow travellers) more indigestion than creole cusine. {btw, my '87 w/ merely 97K mi. consumes @ 600mi/qt around town.}
Trending Topics
06-20-2003, 12:05 PM
#8
according to George this is impossible. Besides, how can you take a guy seriously who cites Taxicab companies as the ultimate proof of quality and longetivity? If that's the case does that make a schoolbus even better than a Chevy?
Last time he talked about his dyno sheet on that SBC he said it was "in his hand but he didn't have a scanner"
sheesh...
rjp
Last time he talked about his dyno sheet on that SBC he said it was "in his hand but he didn't have a scanner"
sheesh...
rjp
