Common issues with S8

[2014AudiS8]

So I bought a 2014 S8 July 2021, in August 2021 the oil seperator went out and I had to get that replaced. (luckily it was under warranty)
After a couple months of driving I ended up noticing an oil leak. I took it into an Audi dealer to get it diagnosed and they told me it was the upper oil pan gasket.
which they quoted me just over $10K for and then eventually came down to $5k.

I am wondering if anyone else has had these same issues?
Are D4 S8's really this terrible of a vehicle? Or did I just happen to get a bad car?

When it was running good, This was hands down the best vehicle I have ever driven and they make me want to get another one.
but I am wondering if I get another one am I just asking for the same issues?

[olympic]

I'm in the market so have been doing some research. I could be wrong but I've not seen that upper oil pan gasket as a common issue.

The biggest issue I've been seeing with all 4.0's seems to be turbo failure due to oil screens clogging which I'm sure you are aware of. With the oil strainer recall in place that should allow that to be addressed if your car hasn't had that fixed already. PCV/separator is another failure point which you already experienced.

Other things I've read that aren't uncommon: thermostat, water pump, motor mounts, control arms and bushings.

Hopefully your S8 is good to you now!

[AncientAudiGuy]

Bought '15 S8 in 2019 wiith 65000 miles on it. Currently have 135,000 on it. Amazing car. Did develop the oil separator squeal at 125,500 (just 500 miles beyond AoA's extended coverage of this issue!). Found a new separator on Amazon for $300, took a weekend to install it. With new seals etc, total cost was about $500. Before this repair, it used to use about a qt of oil between 10K oil changes, afterwards, have never had to add. Noted when I took it apart that the previous owner had the new oil screens installed (and in fact found out that the turbos had both been replaced just before I bought the car). Other than that, been a trouble-free ride. Even though I got some $1000 check from Audi for their "cheating" on EPA mileage figure (the '15 was the highest rated .."27mpg highway"...of all D4's), I actually do routinely get 28-29 mpg (fill-up to fill-up) at 75mph cruising and routinely go over 500mi between fills. As with my previous '91 V8Q and '03 S8 D2, I burn regular gas (87 octane) when the cost of premium is more than 10% over regular... It has B&O sound system, cold weather package, night vision assistant, normal full driver assistance, etc. Wish it had the power rear seats of my D2 and the called/heated cup holder of my wife's '14 Q5 TDI Premium...

[MCP]

Bought '15 S8 in 2019 wiith 65000 miles on it. Currently have 135,000 on it. Amazing car. Did develop the oil separator squeal at 125,500 (just 500 miles beyond AoA's extended coverage of this issue!). Found a new separator on Amazon for $300, took a weekend to install it. With new seals etc, total cost was about $500. Before this repair, it used to use about a qt of oil between 10K oil changes, afterwards, have never had to add. Noted when I took it apart that the previous owner had the new oil screens installed (and in fact found out that the turbos had both been replaced just before I bought the car). Other than that, been a trouble-free ride. Even though I got some $1000 check from Audi for their "cheating" on EPA mileage figure (the '15 was the highest rated .."27mpg highway"...of all D4's), I actually do routinely get 28-29 mpg (fill-up to fill-up) at 75mph cruising and routinely go over 500mi between fills. As with my previous '91 V8Q and '03 S8 D2, I burn regular gas (87 octane) when the cost of premium is more than 10% over regular... It has B&O sound system, cold weather package, night vision assistant, normal full driver assistance, etc. Wish it had the power rear seats of my D2 and the called/heated cup holder of my wife's '14 Q5 TDI Premium...

The price of premium fuel around me is always more than 10% higher than 87 octane, would be nice to be within the 10% mark but I’ve never seen that anywhere.


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[Smoknjoe28]

Bought '15 S8 in 2019 wiith 65000 miles on it. Currently have 135,000 on it. Amazing car. Did develop the oil separator squeal at 125,500 (just 500 miles beyond AoA's extended coverage of this issue!). Found a new separator on Amazon for $300, took a weekend to install it. With new seals etc, total cost was about $500. Before this repair, it used to use about a qt of oil between 10K oil changes, afterwards, have never had to add. Noted when I took it apart that the previous owner had the new oil screens installed (and in fact found out that the turbos had both been replaced just before I bought the car). Other than that, been a trouble-free ride. Even though I got some $1000 check from Audi for their "cheating" on EPA mileage figure (the '15 was the highest rated .."27mpg highway"...of all D4's), I actually do routinely get 28-29 mpg (fill-up to fill-up) at 75mph cruising and routinely go over 500mi between fills. As with my previous '91 V8Q and '03 S8 D2, I burn regular gas (87 octane) when the cost of premium is more than 10% over regular... It has B&O sound system, cold weather package, night vision assistant, normal full driver assistance, etc. Wish it had the power rear seats of my D2 and the called/heated cup holder of my wife's '14 Q5 TDI Premium...

Do you have any problems burning 87 Octane? I don't mind paying the premium for premium, but like others, it's typically 18-20% higher than regular.

[ANMS4]

Bought '15 S8 in 2019 wiith 65000 miles on it. Currently have 135,000 on it. Amazing car. Did develop the oil separator squeal at 125,500 (just 500 miles beyond AoA's extended coverage of this issue!). Found a new separator on Amazon for $300, took a weekend to install it. With new seals etc, total cost was about $500. Before this repair, it used to use about a qt of oil between 10K oil changes, afterwards, have never had to add. Noted when I took it apart that the previous owner had the new oil screens installed (and in fact found out that the turbos had both been replaced just before I bought the car). Other than that, been a trouble-free ride. Even though I got some $1000 check from Audi for their "cheating" on EPA mileage figure (the '15 was the highest rated .."27mpg highway"...of all D4's), I actually do routinely get 28-29 mpg (fill-up to fill-up) at 75mph cruising and routinely go over 500mi between fills. As with my previous '91 V8Q and '03 S8 D2, I burn regular gas (87 octane) when the cost of premium is more than 10% over regular... It has B&O sound system, cold weather package, night vision assistant, normal full driver assistance, etc. Wish it had the power rear seats of my D2 and the called/heated cup holder of my wife's '14 Q5 TDI Premium...

WOW, bought a 100k used car and throws water in it for fuel nice LOL. I get 22-23 MPG on the HYW and run 93 with 3 gallons of E85.

[MCP]

Do you have any problems burning 87 Octane? I don't mind paying the premium for premium, but like others, it's typically 18-20% higher than regular.

As long as you stay out of WOT/heavy boost you should be fine as they probably have octane scaling in their cals and the knock sensors as a last resort to pull timing or cut throttle/boost when needed.


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[AncientAudiGuy]

As was commented, I do try to avoid low rpm high boost when using regular; I have never detected any detonation. I was actually quite concerned with my previous D2 S8. Being naturally aspirated it had quite high CR (11:1). It also had an MTM chip so it was good to about 7300 rpm. Again, when I encountered dealers gauging folks for premium, I would use regular. Had no problem with it, but again, am careful to avoid low rpm WOT. Loved that car...and the sounds of that engine. Sold it in 2 days on Craiglist with 220,000 miles. Other than timing belt changes which I did, never crecked the engine open. Car and Driver had an interesting article/test on regular vs premium fuel a year or so ago (https://www.caranddriver.com/feature...ar-or-premium/). Differences in dyno output, 1/4 acceleration, and mileage were genrally very small and unpredictable.