Second opinion on 996 4S Bore Scoring

I recently took my 2004 996 4S in for an oil change and figured at 90k miles it was a good time to check the cylinders. Sure enough, there's some signs of bore scoring. Id love a second opinion on how bad this is. The car has no symptoms at any time, but I get advice that ranges from "stop driving it" to "take care of it it until you have symptoms which could be years". Would love anyone's opinion that's got some experience. Thanks in advance.

Hate to say it but that's beyond the early stages of the problem. Now you're at a fork in the road. Drive it or repair it or get rid of it. If you drive it, the problem will only get worse in time to the point where your engine starts to consume excessive oil and begin misfiring. And, there is also one big risk for driving it injured... bore scoring is like a cheese grater polluting the oil with metal which acts like sand paper damaging critical components that could have been reused during the rebuild process. You damage the crankshaft journals and that will add another $5K to the job. If don't "love" the car enough to put $25-$30K (or more) into rebuilding the engine or installing a shortblock, you might just be better off cutting your losses and sell it.

Man, all I see are blurry white lines. That's a lot of money to rebuild a 996, considering you can buy them for that or less. Are there any affordable scopes one can buy for home use? I found this one for $32k, good deal? https://www.instrumart.com/configura...0&69623=384466

Quotes source post: 19943181

Hahaha... those people have lost their ever livin' minds... they must work for Porsche AG. Grab one on Amazon for $50 - $125. This one seems to be popular because the camera will articulate thus avoid having to use a mirrored version. Amazon Amazon cheapo version... Amazon Amazon

Quotes source post: 19943217

Oh wow, I was kind of joking about a cheap version, but those are affordable!

Hey, I think I saw and replied to your post on Reddit. Welcome! Drive for now and enjoy. I can show some horror stories and pics of bore scoring if you want. 😬

If you're going through the sump, you'll want the smallest camera head (~4mm) you can find. Many of the cheap Amazon ones are slightly larger (~6-8mm) and more challenging to work through the holes in the cylinder walls.

Think about it this way, you can either keep driving it and eventually have a repair bill that costs more than your car is worth, or you can take that money you'd spend and buy an objectively better 911 without that problem.

My Opinion and Perspective ::: Yes that last pic show the beginning of bore-scoring.......although I have seen much worse cases that were still functioning for intended purpose ..( what is your purpose for this car ??) I would like to know the full history and routine maintenance practice details .....( do you have a full history and used oil analysis tests? ) I honestly think bore-scoring can be prevented .IF you think about it, bore-scoring is ~95% on the bank 2 side. so what is the significant difference from bank 1 to bank 2 ?? The answer is (1) heat and (2) friction (1) Heat :: the bank 2 side is last to get coolant since the water pump is on the bank 1 side and cylinder #6 is the last one on bank 2 and is the most prone to start scoring...Also the heat exchanger/oil cooler is mounted on the bank 2 side right above # 6 Cylinder... (2) friction ::: on the OEM M96 Pistons the wrist pin location is offset 1 mm...This done for a couple of reasons...The main reason is it lessens the "snap load" on the rods when they change directions very quickly at high RPM...another reason for offsetting the wrist pin is to lessen the side thrust load on the piston/cylinder wall during the power stroke...BUT on the m96 they only use the offset to lessen the snap load on the rods, to use for lessening the side thrust load on the pistons/cylinders they would have had to make a bank 1 piston with 1mm offset to the top of the cylinder which they did, but a completely different piston for bank 2 with the 1mm offset to the bottom of the cylinder, which they didn't do...both bank 1 and bank 2 pistons are the same and can be used on either side.......Aftermarket Pistons usually don't have ANY offset so they can be used on either side and have more snap load on the rods, but don't help or hurt the side thrust load on the pistons/cylinders.........The "Ideal" piston design will have a 1mm offset and will be bank specific with offset on opposite sides to counteract the thrust load....But this is more expensive design.... Another thing is Friction also causes heat so HEAT is the main issue that causes bore-scoring....Heat and/or friction will cause the plastic piston coating ( Ferroprint) to fail, once the piston coating fails then you get aluminum on aluminum contact and bore-scoring begins.... Yes there has been a lot of discussion about various contributors to the issue like cold starts and fuel injectors ect....all of which can contribute....but if they were a main cause it would be on random cylinders and not almost always on bank 2 and cylinder #6 specifically... Using high quality synthetic oil with Moly in a high viscosity (50w) will give the best protection against HEAT/FRICTION...and to change it often ....I also think that m96's with Ferroprint would need 1oz per gallon of high quality synthetic 2 stroke top end oil to keep the heat/friction down.... You can continue to drive for a while and get some more smiles out of the 996 , the Root Failure is only about $5k for the highest quality upgraded cylinder/pistons........not a big deal............the rest is labor and "while you are in thers's" that will make the rest of the $30k -$40k ...... If you continue to drive for a few more years I suggest to shorten your oil change intervals, and do used oil analysis to monitor not only the cylinder wear progression but also the amount of metals in the oil that can wear other parts.....when the wear metals get too high.. time to act........

Quotes source post: 19943475

What objectively better 911 can you buy for the price of a 996 rebuild? I�d like to know what sub 30K 911 doesn�t have the possibility of bore scoring. Let�s say it�s 50K if you include the price of the scored 996 and the rebuild. So what 50K 911 is immune to bore scoring and better than a 996? Manual coupe NOT cab automatic of course

Good points. Op, is that last picture cylinder 6?

If you love the car - keep driving it until the motor goes and then spend the money on a rebuild. if you don’t love the car and can’t stomach the expense then sell it now and get something less temperamental. As far as I can tell, every 911 needs a rebuild eventually and every engine costs an eye watering amount to rebuild. The 996/7 Carrera just gets tossed in the garbage because a rebuild puts you way upside down on the cars value.

Quotes source post: 19943868

I would stretch and buy a 996 turbo every single time, especially if you already paid for a C4S. 55-60 does it easy for a manual w driver miles. There's just no point. Early 99-00 cars, esp aerokit I could justify it. The later cars and especially C4S, never.

Quotes source post: 19943613

TC-W3? Salta, ho utilizzato 1/700 di olio TC-W3 (Quicksilver Premium Plus) nella benzina Shell V-Power per 3 anni per aggiungere lubrificazione alla parte superiore del cilindro. Ma non ho mai osato rapporti pi� alti, o aggiungendolo all'olio motore.. ho capito male? 🤔

Quotes source posts: 19942945, 19944078

This is the correct answer. But if you decide to sell, do you disclose the onset of bore scoring? That�s obviously the ethical thing to do but�..you�re losing close to a rebuild cost by selling it with bore scoring. That is reasonable. I was looking at it from the perspective of an early C2 owner not C4S.

Quotes source post: 19944173

Your post is a little hard for me to understand even translated, but I think I know what it is saying... Yes to TC-W3 spec oil ( Group V ).....It is a synthitic Ester based high spec quality oil.... I have always been a fan of Ester oils and here is some history and reasons why... Esters are well known to be the superior in film strength and stable in extreme temperatures...( Natural Esters are even attracted to heat and are magneticaly polar ) Jet engines use full Esters for their high heat properties.. I have used Esters in 2 -stoke Race Bikes and Black Max Outboards since the 70's . Airplanes and Race Cars have had Esters added to their oils for 100 years...and still are today... I use Motul 300 V Competition 15w-50 with Pure Ester Base Stock in my daily 996.1 I recently read an SAE White Paper on a study where they tested a small amount of Ester added to the Diesel Fuel on a Diesel engine and the reduction of wear on the Cylinders/rings was incredible ...I need to go back and get the specifics but I remember it was a very small amount of Ester...way way less then normal doses ... It would be cool if we could get two groups of 996 owners and do a "Trial Study" on the use of Esters in the oil AND in the fuel to prevent Bore-Scoring....... It certainly wouldn't "hurt" anything...

Skip you understood well, thank you (I apologize to all of you, I use google translate to write to you, probably misunderstandings are created). I started using Motul 300V but in the 5W50 grade, I don't use my 996 on the track, but I like to do fast races here in the Dolomites, and I change the oil every month or 5,000 km, so I don't have the problem of long OC intervals. Thanks to the use of UAOS I keep 9 qts of oil, and I don't see big drops in pressure. Regarding the use of TC-W3 1/700 oil on the petrol tank (always and only Shell VPower) I have been doing it on many of my cars for 10 years, and it gives me an extra guarantee due to the esters, the lubrication and cleaning of the upper part of the cylinder, and the tangible effects on the fluidity and silence of the engine. (I'm Igor from Venice - Italy, we've been in touch several times by email , I got your UAOS 12/2022, I'm advertising it and pointing it out to many friends here in Italy - someone should have written to you and bought it in recent times. It's always a great pleasure and culture to read you Skip, sincere thanks for every contribution you make )

Quotes source post: 19945646

Hi Igor thanks for connecting me with your screen-name , yes I remember your E-Mails...and thank you for promoting the UAOS System in Italy by word of mouth. .. I don't do any advertising but I have shipped UAOS System kits to others in Italy and all over Europe, Asia, Africa and Canada ...... Some particular countries place high Customs on the UAOS System that increases the cost to 996 owners for the UAOS System that is coming from the US which is unfortunate as I have tried to keep the price the same over the last few years, but as cost of production and materials/supplies have increased dramatically I am forced to plan on increasing the price next month...Plus since "perception is reality" and the Porsche Motorsport AOS is more costly than the UAOS System many people believe the MAOS is better but the fact is the UAOS System is much much superior and changing the price to he higher than the MAOS will change the perception.....I can also give discounts to Rennlist Members and do periodic Sales Specials like Black Friday Deals, Anniversary Deals ect...... I have recently been in talks with LN Engineering as I'm getting really old about transferring the rights/responsibility's of the UAOS System and the Twin Tunnel Port/UIDS to them as I am unsure if keeping up with demand and training new people to do things exactly like I want is good or bad for my old age.... Igor I honestly think your engine will be one of the ones who never has bore-scoring...Seems like you are doing the right things that will prevent this from effecting your engine...I'll put you in my " unofficial Trial Study" on Bore-scoring .... Just to be clear... not all TC-W3 oil are Esters....but the QuickSliver Premium Plus IS and is what I use in my Black Max V6 2-stroke Outboard .....and all my other OutBoards.. Yes Esters cost more than mineral oils or even other Synthetics that mimic mineral oils...I have $300 worth of Motul 300V ( 3-5liter cans) sitting by my desk now... One more thing about my experience with Esters as a fuel additive...back in the 1980's in my World Record Holding Turbocharged Mechanical Fuel-Injected Alky-Burning race car...I used a Bo Laws Ester Top End Lube...Running pure methanol the cylinders/rings need lube as the Methanol is very dry...,Bo Laws ( now an NHRA Hall of Famer) at the time had a Ester Top End Lube he sold to us Alky users...I would buy Methanol by the 55 gal barrel and his Top End Lube by the case......and mix it as needed...Methanol was only good after opened for a few months so any fuel left over would get put in the daily drivers/work trucks/lawnmowers ect....I was making E-10 E-15 long before the Government mandated it for passenger cars..lol So again my opinion is the whole Bore-score problem is simply due to localized heat/friction.on the bank2 + Cylinder #6 and the simplest way to prevent it is the toughest film of oil that doesn't thin out as much from heat/friction....so higher viscosity+ Ester in both the oil and fuel seems to be the easiest/quickest/least expensive solution.....Of course re-designing and upgrading the entire cooling system to run at a lower operating temperature at ALL Times would work also but much more effort and much more cost..

To the OP ..I'm trying to understand bore scoring at 90K ...I see that you reside in a colder climate and you stated that you would warm up your C4s properly I'm assuming start and go but under low rpms ?