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Before I dive into the details of the problems with my engine. I first want to say this forum has been very helpful, and it has helped me identify the current problem with my engine.
There was a post a couple of months back on how much oil does your 997.1 consume. Not knowing anything different I posted that my car consumes a quart every 2,500 miles. From other threads I read I thought that a quart of oil every 2,500 miles was okay. Almost immediately I received a response from cwheeler stating that it is not normal for a rebuilt engine to consume that much oil. Thanks to cwheeler I called my local indy and explained the oil consumption and they told me to bring in the car to have the engine checked out.
It was confirmed fairly quickly that oil was past the rings in two of the cylinders, but they could not determine the reason for the leak until they took the engine apart. After a few weeks I heard back and found out that I also have bore scoring on three of the cylinders. The car has around 5K miles since it was rebuilt at a Porsche dealer in Sept 2019. The dealer sent the engine to L&N Engineering where it was bored out to a 4.0 with new pistons bearings, IMS bearing etc.
When I bought the car in January 2020 it had 500 miles since the rebuild, and the owner provided all the documentation of the rebuild. I am pretty sure the seller was unaware of the problem when he sold the car.
This is my first Porsche and the one good thing is that I really enjoyed the car this past summer. The plan is to rebuild once again and enjoy my 4S for many more years.
After what I have experienced I recommend that you check for bore scoring in the PPI even when the engine is rebuilt.
What a horror story. Scoring 5,000 miles after a full rebuild. There are 997's out there with well over 100,000 miles on the original engine with no scoring. As an aside and not that it will help you in any way but I think Porsche considers as much as a quart every 600 miles as being within their perimeters. RL member Edgy took European delivery of a new 2006 C2S. If memory serves, his car has used a little over that amount since brand new. He's up there on the miles on the car now but oil burn hasn't changed, nor has anything else over the years. At least not reported by him unless I missed it.
Good luck going forward. Seems like some goodwill from whoever did the rebuild would be in order here.
A lot of people think Porsche says it’s 1 quart per 600 miles, but that’s not true according to the below in the owners manual. Porsche actually says burning 1.6 qts per 622 miles is acceptable. That works out to 1 quart per 389 miles! I bet a lot of folks who don’t read these forums are running around burning a good amount of oil and have scoring already but are not worried because their owners manual says it’s normal, and these engines will still last well over 100k miles. I think there are also a lot of folks who read these forums who are rebuilding their engines a little prematurely because they found a little scoring. If you’re gonna spend $25-30k on a rebuild, why not wait until your engine fails though is my question.
Originally Posted by sandwedge
What a horror story. Scoring 5,000 miles after a full rebuild. There are 997's out there with well over 100,000 miles on the original engine with no scoring. As an aside and not that it will help you in any way but I think Porsche considers as much as a quart every 600 miles as being within their perimeters. RL member Edgy took European delivery of a new 2006 C2S. If memory serves, his car has used a little over that amount since brand new. He's up there on the miles on the car now but oil burn hasn't changed, nor has anything else over the years. At least not reported by him unless I missed it.
Good luck going forward. Seems like some goodwill from whoever did the rebuild would be in order here.
Last edited by Carreralicious; Dec 14, 2020 at 09:43 AM.
Its like porsche knew these would score and gave them this crazy spec.....
Originally Posted by Carreralicious
Yeah, or even if not scoring, it would cover any other engine ailment till at least the warranty expired.
Honest and forthright aren’t what the savvy Porsche board is looking for in their executives. Just another splashy corporation selling a high-end brand’s planned obsolescence.
A lot of people think Porsche says it’s 1 quart per 600 miles, but that’s not true according to the below in the owners manual. Porsche actually says burning 1.6 qts per 622 miles is acceptable. That works out to 1 quart per 389 miles! I bet a lot of folks who don’t read these forums are running around burning a good amount of oil and have scoring already but are not worried because their owners manual says it’s normal, and these engines will still last well over 100k miles. I think there are also a lot of folks who read these forums who are rebuilding their engines a little prematurely because they found a little scoring. If you’re gonna spend $25-30k on a rebuild, why not wait until your engine fails though is my question.
This topic is an evergreen, and of course the maximal oil consumption in the user manual is not what you want in your own car.
But below is a page from the actual Porsche workshop manual showing that they expect a healthy engine to consume no more than 500cc per 1000km, or 0.85 quarts per 1000 miles. So this is 3 times less than what they state in the user manual.....
(It also shows that a healthy engine should have 5 bar oil pressure at 5K rpm at operating temperature, again better than the coy 3.5 bar in the user manual.)
But from all I've seen, including the poll in this forum, the scatter of oil usage is enormous and 1 quart per 2500 miles would not have raised any red flags for the original engine. Probably, with such low miles, one would have waited for everything to brake in properly.
The more important criterion is whether the oil usage changes in time, and do you get sooty pipes. Weird, hope it works out for you.
Last edited by roadie13; Dec 14, 2020 at 11:10 AM.
Thing is most owners will not have access or try to look at what the shop manual says is normal and instead will rely on what’s in their user manual. But I agree, if I saw an oil burn rate of up to 1 qt per 389 miles, I certainly wouldn’t see that as within acceptable specs. Whatever Porsche deems acceptable is moot I think, as what they put in their manual is what they are telling owners is acceptable whether or not it really is.
Originally Posted by roadie13
This topic is an evergreen, and of course the maximal oil consumption in the user manual is not what you want in your own car.
But below is a page from the actual Porsche workshop manual showing that they expect a healthy engine to consume no more than 500cc per 1000km, or 0.85 quarts per 1000 miles. So this is 3 times less than what they state in the user manual.....
(It also shows that a healthy engine should have 5 bar oil pressure at 5K rpm at operating temperature, again better than the coy 3.5 bar in the user manual.)
But from all I've seen, including the poll in this forum, the scatter of oil usage is enormous and 1 quart per 2500 miles would not have raised any red flags for the original engine. Probably, with such low miles, one would have waited for everything to brake in properly.
The more important criterion is whether the oil usage changes in time, and do you get sooty pipes. Weird, hope it works out for you.
Do you accept any vehicle you own, outside of your 911, to burn oil at the rate that most people find acceptable that their 991 burns.
I buy cars (daily/work driver)every 4-5 years, typically under 50k miles, and run the until roughly 250-350k before I sell. So I don't know how these cars are taken care of before I buy them. None, and I repeat NONE burn oil at a rate anywhere near, what this board seems to find acceptable. The worst burner was my last car, a 2009 Jetta. Burned about a half quart per 5000 miles. Changed the oil every 10k. All my previous cars burned so little I didnt have to add any between changes....
Why do people accept their 911 engine burning oil at the rates the manual states, or worse? If your car is burning oil, something is wrong. The OP was biting a quart per 2500. That is insane. I'm glad he got the car looked at.
Perhaps, @cwheeler, it's partly due to the legacy of the air-cooled engines, which burned more oil and in a fashion more related to climate, driving style, etc.
My 993 C4S was great at oil consumption, but based on others' comments/feedback, etc., I was always prepared to add quart. The "noise" was louder than the reality, at least for me.
That's the only thing I can think of, and I may be totally wrong.
Do you accept any vehicle you own, outside of your 911, to burn oil at the rate that most people find acceptable that their 991 burns.
I buy cars (daily/work driver)every 4-5 years, typically under 50k miles, and run the until roughly 250-350k before I sell. So I don't know how these cars are taken care of before I buy them. None, and I repeat NONE burn oil at a rate anywhere near, what this board seems to find acceptable. The worst burner was my last car, a 2009 Jetta. Burned about a half quart per 5000 miles. Changed the oil every 10k. All my previous cars burned so little I didnt have to add any between changes....
Why do people accept their 911 engine burning oil at the rates the manual states, or worse? If your car is burning oil, something is wrong. The OP was biting a quart per 2500. That is insane. I'm glad he got the car looked at.
Cw
My 2006 Acura TSX with 200K on the odo burned about 2 quarts between changes at 5000 miles. It burns less now that the top end has been rebuilt but still uses some. MDX burns zero and I only use Mobile1 0W-20 too. Previous rides have burned more or none at all. It varies. My 911 burns about a quart every 2500 miles. Not concerned. Had my indy check fuel trim and its normal. AOS is creating correct vacuum. I might have a cracked hose somewhere but I won't go searching for it unless things get a lot worse. I had bores inspected at 80k spark plug change and the indy said they are fine. I'm just enjoying the ride!
