Replace cylinder head

Mechanics did bore scoping found no bore scoring but oil contamination in all cylinders from value guides and seals. Estimate is 13k labor plus parts. 94k miles. Deciding wether worth the expense or new flat 6 innovations engine.

Did they do a leak down test? Are they sure its guides and seals or have the piston rings worn? Does the engine still run reasonably or not?

Yes did leak down test compression good. No sign or scoring. Had misfires periodically, very periodically. engine runs very well.

Personally I'd probably run some thicker oil and just run it. I assumed they checked your AOS at the same time. Save for the big bore rebuild sometime in the future, but it might be years away

I am 70 so years away gets complicated.

fair enough then, then go for it get the biggest capacity you can

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So you think might as well spend more and get new flat 6 innovation engine?

If you have the means to! I'd love a 4L in mine, one day it will happen.

What were the symptoms that led to this diagnostic? The only reason to rebuild the whole thing is if you want more power. It will take more time and many more dollars, but I can assure you, the transformation is amazing!

Yeah that could just be a bad AOS or something. Maybe worth a second opinion.

If a leakdown was performed and it was good, then I think that suggests ring seal and valve seating is adequate. So, I guess the next question is how much oil are you burning? How quickly are you consuming oil? Bad valve seals would suck in oil on deceleration --- are you noticing smoke on decel? Bad valve seals would tend to be worse when cold, so does the car make a lot of smoke when it starts and then less when it is warm? The valve seals will expand when they warm up, so less oil might leak past when the engine is warm...oil from leaking valve seals would tend to get burned off during engine operation Was a compression test performed as well? Bad rings usually smoke taking off from stop lights, accelerating, etc. As mentioned, it could be a bad AOS and not valve seals at all, or only partially. It seems like a lot of money and only end up with new valves and valve guides and stem seals. If it were me I would call one of the popular and trusted engine rebuilders and discuss the options with them. It might be worth it to just get a basic rebuild (seals, rings, bearings, oil pump, water pump, hoses, belts, sensors, RMS, IMS, ...) and add a UAOS and a deep sump and run it another 100k miles.

I�m very happy with my Hartech rebuild from Slakker just to throw it out there. Brandon is a great guy to work with and knows his stuff.

OP hasn�t even mentioned oil burning/consumption, only that a bore scope �found oil contamination in all cylinder�. Honestly if there is no problem in use then the diagnostic might be the problem�

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Never heard the words " oil contamination " used like you did above. You sure thats how your mechanic stated it..? Most times a mechanic uses that term its because of intermix. How does the oil on dipstick look, does it look like a brown milkshake...? How does the coolant in your reservoir look...? Anyhow, the most common reason for a M96 head to need R&R is from intermix cracks.... Not valve guide/seal problems. Especially if a good leak down test and a good compression test were completed successfully. And have normal oil usage with no smoke... You might want to go over your mechanics diagnosis again with him. The words you used and the $13K cost estimate don't make sense to me. A total head stage 2 port job with all new valve guides and all new valve seats and top line valve job, cost about $5000.00 for both heads, from the best m96 head guy in the USA, Len Hoffman. That leaves $8000 for the engine out and head removal/replacement. Thats outrageously high and would not correspond to any normal labor/work cost specs... Now with new Porsche heads,,, that makes more sense. Do you have a written estimate/diagnosis of work needing to be done...?

I agree. However, perhaps the mechanic meant to say 'cilinders were contaminated with oil'? I.e. valves and piston tops glistening from oil that had leaked past valve guides and their seals. @Dfsavgny did the mechanic share pictures of the bore scoping with you? Then consider sharing them here.

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Flat 6 isn't the only game out there. AFAIK they have a long waiting list (lead time?) for builds. That is just from what I see on RL, comment/correct if mistaken. If you decide for new engine, the Slakker 4.1L is a pretty potent engine and may cost less than F6, dunno. Call or reach out to Brandon Clark at Slakker (sr.dev) and explain, talk about what you would like, want, realistic expectations, and so on. Look at their web page for some general details and numbers. When I was there at Slakker, they had 29-32 p-cars, Many engine cores, parts galore, and shop going very well. On an engine job they had faaaaar lower cost recondition rods, spare valves, bits and pieces to give owner $ options for repair. As mentioned, inspect the AOS, and generally condemn it. Get a UAOS with track drain + 997 oil drain tubes and put that in your "repair mix". UAOS fixes oil problems, the P-Motorsport version does NOT. Age 70 is not detrimental, my opinion in same boat. My "boat" is not sinking or leaking. Sure, rebuilding takes time and $$, and it may take some weeks to get it finished, but they can do it even with the sea of 996/7/Caymans/Boxsters there. Just my observation & opinions. YMMV

How many miles are on this engine? M96 motors will eventually ovalize the cylinders and there is only one fix for that.

Given that good machine shops are backed up and take a long time to finish the valve job (6-8 weeks), and the top grade valve job runs $5,000, I would just buy the two heads from Porsche for $7-8K (they will discount them to get your business), and spend 20 hours to put them in.