VONBOTTLE

as a fairly new owner of an '08 S6 i've got a couple maintenance questions - on my A6 2.7 i always used M1 0w40 oil, does the V10 prefer a different viscosity? bear in mind i'm in CT so, not quite the north pole but it can get pretty cold up here. are there any oils that can help reduce the carbon build up i've read about? i've been looking at Motul 8100 x-clean or x-cess, obviously a bit more expensive, but in the broad spectrum, what's an extra $50 for an oil change when i do it at most twice a year since i don't put a lot of mileage on. would an ester based oil like redline or motul 300 be even more preferable? i've been researching it a little recently but haven't found much info. obviously price starts to get up there with ester based, around $140ish for redline and $180ish for motul 300.

regarding carbon buildup, i bought the car with 88k miles on it, i have no service records, but the engine runs very smooth, no misfires, no idea if the previous owner had cleanings done, but when the time comes to getting a cleaning, would it be worthwhile to simply replace the valves with new? how much labor is involved in cleaning the 10 valves? 10 new ones will run around $400, obviously there's more than just the valves that require cleaning, but just curious about that.

cnyman

Well, regarding another oil that might reduce deposits, I don't have an opinion. There is massive information on what is a good vs not so good oil and the reasons behind the analysis. Try searching the S4 forums as I recently read a post on this topic. I am personally wondering if valve seal integrity might be a factor in the build up and perhaps the factory seals might be to blame for some of the issue. All the DI engines build up deposits but if the factory installed seals are iffy, then this could explain a lot. I am currently replacing all of the valves on my 3.2 and will check the deposits after another 30k to see if there is a difference with new valves and seals.

I can speak to the concept of replacing valves. Essentially, you would be paying for new seals, potentially refacing the seats to match the new valves, testing of all the springs removal and installation of all the misc items that are bolted to the head, cleaning and the labor to pull the engine. Most would recommend that the timing chain guides and tensioners should be replaced since the heads would be coming off. Regarding the cost, I think you could probably buy a very nice used A6 for what it would cost. Worse yet, you would be tearing into a perfectly running engine and that always brings the potential to make something worse than when you started. If funds are unlimited, then go for it but the cleaning is done from the intake chambers with soda blasting/scraping and that seems to hold for roughly 50k. By the way, it has 20 intake valves (2per cylinder). I would get a quote from and independent shop on the cleaning but a complete valve job with the valves and the associated parts would be at least 5k if not a lot more( I am guessing). The V10 is not a common engine so parts are even more ridiculous than the normal ridiculousness. A heads up, bullstuff.com sells a lot of engine parts cheaper than most. Honestly, the costs involved are so severe that buying a lower mileage vehicle would have made more sense. I would "drive it like you own it" until you find issues with driveability.

VONBOTTLE

oh yeah, duh! 40 valve engine, 2 intake valves each........i figured it was kind of silly question - obviously a bit more involved than i thought.....i obviously didn't sleep at a holiday inn last night! thanks for the input, i'll check out the S4 forums as well

AndreNY

its $1000 to do a carbon cleaning why would you change valves??

VONBOTTLE

i didn't totally think my question through - was just wondering how much labor was involved to clean the valves themselves versus cost of new valves, but for some reason was only thinking 10 valves not 20, not to mention other related parts/labor.....but $1k for the cleaning isn't outrageous, not great, but it is what it is.

uberwgn

Von, the newer VAG spec oils, known as 504/507, have a 'change in mass' limitation written into the description for the intake valves. These newer oils should be leaving less deposits in the combustion chambers, on the valves and in the ring zones.


ALL 504/507 oils are 5W30 by definition.

hrc4u

just to be clear here...cnyman trashed his valves on driver side i recall reading...due to the tensioner issue.....so thats probably why he mentioned the valve replacement... =)
cheers!/H