S4 reliability @ 80-100k+ miles (inc. sport diff/ADS)

Rovofob

Registered User
Hi everyone,

As a serial BMW driver and hopefully soon to-be S4 owner, I thought it was time I made an appearance here. I’m looking to get a B8 S4 Avant manual, although the S5 V8 is still tempting...

I’ve read loads of S4 threads here, on Pistonheads and elsewhere, but most of these seem to be focused on S Tronic or facelift models, with many of the manual ones being from years back when the cars were much newer.

However, I’m looking to understand what to expect from a 10-year old, 80-100k+ mile model. Can these be a good buy, or do they become something of a money pit with particularly big bills/servicing milestones to watch out for? And are previously desirable kit like the sport diff and ADS worth having or do these become a liability, likely to throw up huge bills?

Everyone raves about the sport diff and adaptive suspension, but is there a particular age/mileage that these need servicing/replacing and what’s the typical cost for that? Having the diff appeals, but will steer clear if they’re starting to cost many thousands to service/replace. Also, how many miles/years do the clutch/flywheel typically last and what would you expect to pay to replace these?

I’m happy to put some money in to maintain an S4, but would be good to have an idea of how much might be needed and when!

Many thanks for your insight. I’m sold on the idea of an S4, just want to make sure buying a 10-year old model isn’t more trouble than it’s worth. Cheers!
 

Tobe

Registered User
Good buy, mostly.

If you want a manual you don't have the gearbox to worry about.

Sports diffs are pretty strong I've never had one go wrong, there's no servicing for them but around 100k I would definitely replace both fluids if it's spots diff or even just standard probably change out the fluid.

The engines are pretty bullet proof as long as they've had proper maintenance, common problems are timing chain upper tensioners on the pre 15 (ish) cars, cause a rattle on startup, all 3 I've had had done this and I've covered 60k+ miles between them and never had any issues, it's just cosmetic in my opinion on startup and then that's it. Some people really worry about this but personally I wouldn't let it put you off one when buying.

The main bottom crank pulleys have been known to separate as they have a rubber dampening section, which can cause damage depending what rpm it goes at, so may be worth changing if not done already. And water pumps and pcv vakves on certain years, but if your buying at that mileage those should have already been done, normally under warranty pretty early on.

As above I've had 3 b8 models, so pre 2013, all bought between the mileage you're looking at and not had a single "major" issue, all were stronics, with full drive select, so the diff, suspension and steering as well so really taking maximum risk!

Hope that helps.

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Rovofob

Registered User
Good buy, mostly.

If you want a manual you don't have the gearbox to worry about.

Sports diffs are pretty strong I've never had one go wrong, there's no servicing for them but around 100k I would definitely replace both fluids if it's spots diff or even just standard probably change out the fluid.

The engines are pretty bullet proof as long as they've had proper maintenance, common problems are timing chain upper tensioners on the pre 15 (ish) cars, cause a rattle on startup, all 3 I've had had done this and I've covered 60k+ miles between them and never had any issues, it's just cosmetic in my opinion on startup and then that's it. Some people really worry about this but personally I wouldn't let it put you off one when buying.

The main bottom crank pulleys have been known to separate as they have a rubber dampening section, which can cause damage depending what rpm it goes at, so may be worth changing if not done already. And water pumps and pcv vakves on certain years, but if your buying at that mileage those should have already been done, normally under warranty pretty early on.

As above I've had 3 b8 models, so pre 2013, all bought between the mileage you're looking at and not had a single "major" issue, all were stronics, with full drive select, so the diff, suspension and steering as well so really taking full risk!

Hope that helps.

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Thanks for that - really, really useful.

In terms of the gearbox, is there a set typical mileage for needing changing? Have seen one that had the clutch changed at around 80k, but no idea if that was the first or second clutch change.

Good to hear sport diffs are robust. Won’t avoid models with that then. Sure I saw something about £5k-£10k repair bills somewhere...Changing fluid sounds wise - imagine that’s several hundred pounds rather than more than that.

Sounds like B8 chain rattle is a completely different kettle of fish to B6/B7 chain rattle then, which is good. Is the bottom crank pulley a big job? As for water pumps this is a one-time fix then? Poor quality standard one should have been fixed way back and newer design should now be fine?

Glad to hear you didn’t have any big.problems with all the potentially pricey electronic bits and bobs fitted!

On a different note, would having an MRC Stage 2 remap dramatically reduce the life of any parts? Imagine clutch/flywheel and brakes may have may have a harder time and no last quite as long, but would hope this wouldn’t destroy anything...
 

Tobe

Registered User
Sorry I have no experience of the manuals, so clutch changes I have no idea. It will be pretty much the same as any other car though, as in completely dependant on how well it's been driven, and the type of driving in general.

Yes, Don't get me wrong if something did go wrong with any of the ads options, it would very likely be very expensive. But I can only speak from my experience, maybe wait for some other to come along who might have more experience of issues.

I did all the fluids myself on the last one, it's not to difficult, and total cost for both diff fluids was about £30, but it is probably about 2hrs labor so at a garage easily £200.
 

Tobe

Registered User
Sorry and yes totally not the same issues with chains as the 4.2 engine. And my first one I had MRC do a stage 2 package, brilliant. The last 2 I have just stick a stage 1 tune on.

I don't think people have issues running higher power, I haven't. The only thing to note is potential wear on the s/charger as it will be spinning fast on stage 2 with different pulleys. There I a small oil reservoir on the s/charger that can be serviced, kits on eBay to replace this it's a very small amount of oil, but might be worth doing if worried. But no in general I don't think anything is likely to go.
 

Rovofob

Registered User
Sorry I have no experience of the manuals, so clutch changes I have no idea. It will be pretty much the same as any other car though, as in completely dependant on how well it's been driven, and the type of driving in general.

Yes, Don't get me wrong if something did go wrong with any of the ads options, it would very likely be very expensive. But I can only speak from my experience, maybe wait for some other to come along who might have more experience of issues.

I did all the fluids myself on the last one, it's not to difficult, and total cost for both diff fluids was about £30, but it is probably about 2hrs labor so at a garage easily £200.

Thanks Tobe. Doesn’t seem like clutches are a weak point, so that’s the main thing. Sure, it’s tricky gauging the likelihood of any big money issues with any car. It’s always a good sign, though, if some owners at least have come through unscathed!

Might give Audi a call and gauge what they’d charge for changing the suspension/diff. A good indication of the maximum they should cost anyway. Imagine the figures may be quite scary...Found some Sachs electronically controlled dampers that came in at £1,300. No idea if they’re OEM, but not as bad as they could be, I suppose.

Anyone had to replace the sport diff/ADS?

Doesn’t sound bad for diff fluids. Not something to worry about in the world of used Audi’s that were £40k new! Phew, glad it’s not the same chain issues as the B7. Everything I’ve heard about MRC Stage 2 has been very positive. Looks super powerful but torquey too. How did you find the Stage 1 tune?

Sounds like a wise move checking out the supercharger condition just in case. Cheers for your thoughts.
 

jdp1962

Grumpy Old Man
Thanks Tobe. Doesn’t seem like clutches are a weak point, so that’s the main thing. Sure, it’s tricky gauging the likelihood of any big money issues with any car. It’s always a good sign, though, if some owners at least have come through unscathed!

Might give Audi a call and gauge what they’d charge for changing the suspension/diff. A good indication of the maximum they should cost anyway. Imagine the figures may be quite scary...Found some Sachs electronically controlled dampers that came in at £1,300. No idea if they’re OEM, but not as bad as they could be, I suppose.

Anyone had to replace the sport diff/ADS?

Doesn’t sound bad for diff fluids. Not something to worry about in the world of used Audi’s that were £40k new! Phew, glad it’s not the same chain issues as the B7. Everything I’ve heard about MRC Stage 2 has been very positive. Looks super powerful but torquey too. How did you find the Stage 1 tune?

Sounds like a wise move checking out the supercharger condition just in case. Cheers for your thoughts.
Hi, personally I wouldn’t be asking an Audi dealer for quotes for this kind of work on a ten-year old car. It’ll be prohibitively expensive And pretty much everything can be done just as well by a good reputable independent. Depending where you live, there are quite a few indies that specialise in VAG brands.
 

Rovofob

Registered User
Hi, personally I wouldn’t be asking an Audi dealer for quotes for this kind of work on a ten-year old car. It’ll be prohibitively expensive And pretty much everything can be done just as well by a good reputable independent. Depending where you live, there are quite a few indies that specialise in VAG brands.

The logic of getting Audi quotes was to have an idea of what the maximum cost could be - I would imagine going to an Audi specialist for most things. However, I’m not sure of the likelihood of being able to get a replacement sports diff from elsewhere - especially as I understand that Audi engineered this part itself, rather than getting a provider like Bosch to develop it, which is often the case with less complex parts.
 

scotty76

Registered User
Sports diff is a bit of a pain to find on second hand cars as dealers tend to either not list it or claim it has it when it doesn't! My old S4 is still up on Autotrader (I part ex'd it) and definitely has sports diff as I had it from new and specced it! :) But it isn't listed on the advert.
 

Rovofob

Registered User
Sports diff is a bit of a pain to find on second hand cars as dealers tend to either not list it or claim it has it when it doesn't! My old S4 is still up on Autotrader (I part ex'd it) and definitely has sports diff as I had it from new and specced it! :) But it isn't listed on the advert.

I’ve found one manual with sports diff, another with at least Drive Select, but that’s it. Yep, so many car dealers are thoroughly inept! It’s a wonder they manage to sustain a business.

Have to say, though, the last dealer I dealt with - the place I bought my current Subaru Legacy 3.0 R Spec B - was fantastic. Price, service and transparency were all very good. So much so I’m wondering whether they’d buy it back when I find a suitable Audi...
 

scotty76

Registered User
Just watch for the road tax on the manuals. It's usually a lot more than the S-tronic for reasons that were never clear to me. In 2014 when I was looking the manual was nearly twice as much!
 

Rovofob

Registered User
Just watch for the road tax on the manuals. It's usually a lot more than the S-tronic for reasons that were never clear to me. In 2014 when I was looking the manual was nearly twice as much!

Yes, I’m aware, thanks. Very frustrating, but I definitely want a manual, so that’s a cost I’ll have to pay - unless I can find a suitable 2009 manual saloon - the emissions on those are just low enough to be £330 to tax.

Was at one stage considering having a sensible car and something fun - in which case I wouldn’t put up with tax over £500 for the sensible car - but the S4 Avant sounds like it could be a satisfying to drive one-car solution. In which case £550-ish road tax is bearable.

Either that or I go for an S4 B7, benefit from lower tax and put money into a cam chain fund!
 

Dippy

Registered User
I'm not sure how much I can add.

In case you weren't aware from the UK B8.5 facelift model in 2012 s-tronic was the only option for the S4.
Sports diff is rare. Manuals are uncommon. Getting one with both is going to be super rare so the one you have found might be your only option.
I think you're right that like the rest of the transmission the sports diff is a VAG design. But I don't think they are crazy expensive. I haven't read of many sports diff failures reported on my time on the forums.
I haven't paid a lot of attention to manuals - but I do see some owner reports over on Audizine. IIRC it is common for the clutch to need doing at around 80K.
Gearbox oil changes are often missed. Also Audi specify that gear oil, as well as the ATF on the sports diff is lifetime. So sometimes its hard to get a dealer to do the change so you may have to go indie. I have just had my sports diff oils changed (@ 5 years/21K) and the cost was around £100ish.
I think the main issues have been mentioned above apart from the timing chains. I don't know how bad they were on the B6/B7 but there have been plenty of cases of rattle on older B8s. It seems fixable but unfortunately is still a significant cost.
 

Rovofob

Registered User
I'm not sure how much I can add.

In case you weren't aware from the UK B8.5 facelift model in 2012 s-tronic was the only option for the S4.
Sports diff is rare. Manuals are uncommon. Getting one with both is going to be super rare so the one you have found might be your only option.
I think you're right that like the rest of the transmission the sports diff is a VAG design. But I don't think they are crazy expensive. I haven't read of many sports diff failures reported on my time on the forums.
I haven't paid a lot of attention to manuals - but I do see some owner reports over on Audizine. IIRC it is common for the clutch to need doing at around 80K.
Gearbox oil changes are often missed. Also Audi specify that gear oil, as well as the ATF on the sports diff is lifetime. So sometimes its hard to get a dealer to do the change so you may have to go indie. I have just had my sports diff oils changed (@ 5 years/21K) and the cost was around £100ish.
I think the main issues have been mentioned above apart from the timing chains. I don't know how bad they were on the B6/B7 but there have been plenty of cases of rattle on older B8s. It seems fixable but unfortunately is still a significant cost.

Yes, writes off all the B8.5s for me. In reality the only thing I think I’d miss is the sound generator and a sensible 160mph speedo compared with the idiotic 200mph one - what’s the point when you can’t legally use two thirds of the speedo?!

Yep, I’m learning just how rare manuals with sport diffs are. Can compromise on not having the diff, but manual is crucial. I saw a Pistonheads post about someone needing a new diff a few years back and the part alone costing £6k. Has put me off somewhat, though that was only the one car.

80k sounds reasonable for a clutch. Are gearbox oil changes for manuals, too? As for the timing chain, what’s the repair for the rattle - does it need one, or is it just an annoyance? Thanks.
 

Dippy

Registered User
Sorry, I can't add any more other than suggest you have a search on Audizine - there are lots of US-based owners with 6MT on there.
 

Rovofob

Registered User
Sorry, I can't add any more other than suggest you have a search on Audizine - there are lots of US-based owners with 6MT on there.
No probs. Will have a look. Thanks.

Will look into warranties, too, as that might be another solution - don’t worry about the spec, just make sure there’s sufficient warranty cover to fix any super-pricey issues without four-figure bills...
 
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