Modern Autobox reliability

[WaspsNest]

tl;dr - Are modern day autoboxes any good, or still avoid-like-the-plague bad?

Evening ladies & gents,

I do a lot of miles, minimum around 1300 a week. All of this is spent in various dull diesels due to being company cars; it's also a 50/50 split with A roads and Motorway slogs.
I may be getting rid of the company car and due to a job change, having to buy my own. I've always loved the relaxed way autos seem to waft along, but I've always been concerned about reliability and replacement costs of them if they decide to disintegrate (I had a bad experience with Subaru's 4EAT...need I say more - albeit a bad example)

If I was going to go for an auto, I'd aim to buy one of these, and pummel it into the core of the earth with the next owner being a scrap yard:

Citroen C6
Post 2005 E-class Merc (E220/270/320 cdi)
E60 5xxd BMW

If I got one of the above, I'd like it to last a few years before explosion, If I was buying any of these, I'd be looking at sub 80k mileages to ensure partial reliability throughout its tough life. My conclusion was, that on a manual - it's cost you c.£1200 on one of the above to get a Dual Mass and Clutch done, but about £1500 to get an auto reconditioned, so they are both as reliable as each other in the long term?

Perhaps I'm a being naive - but if anyone will give me good answer based on experience, it'll be you guys.

Thanks in advance for your $0.02.

[devnull]

234k in my Merc V6, owned it since 83k. Don't think the oil has ever been changed, certainly not in my ownership. Testing the 'sealed for life' bit to the extreme

The 722.6 'box is a good one.

[slinky]

Ask redvictor which he repairs the least of!

[jamesh764]

The Citroen C6, in common with lots of other cars, has the autobox built by Aisin Warner, a Toyota subsidiary.

Mine is coming up to 80,000 miles and needs the hydraulic valve block replacing, which is going to cost in the region of £1500.

Including me, I know of four people who have had cars with this gearbox, and two have had the same problem. So, based on a really small sample size, I would say no, auto gearboxes are not reliable. Well, not the Aisin AM6 anyway.

[WaspsNest]

Dammit, the C6 is a lovely chunk of metal too, no? Shame to hear that.

jamesh764 said:

The Citroen C6, in common with lots of other cars, has the autobox built by Aisin Warner, a Toyota subsidiary.

Mine is coming up to 80,000 miles and needs the hydraulic valve block replacing, which is going to cost in the region of £1500.

Including me, I know of four people who have had cars with this gearbox, and two have had the same problem. So, based on a really small sample size, I would say no, auto gearboxes are not reliable. Well, not the Aisin AM6 anyway.

Good going on the high-miler merc ^^ though, damn good.

[redvictor]

In order worst is first.


BMW
Citroen
Merc.

All modern transmissions are failed mostly by their electronics.
They also fail via the trans cooler allowing water into the trans.
BMW ZF transmissions are way better than the GM5L40 they put into various BMW's.The GM trans is the usual piece of crap from the Strasbourg plant in France. There is not enough room on the page to list the faults they have.
ZF's suffer from the Mecatronic unit(6 speeds), and fwd drum,rev pistons, VB cracks (5 speeds).

Merc 722.6 transmissions have their failings, which include,planetary bearing failure, speed sensor failure, Converter lock up issues.

Citroens have a ZF4HP20 or a DPO trans.The ZF has pump issues,along with VB problems.
The DPO has very common pressure regulation issues and fwd band breakage.
It's not a bad trans apart from that.
The later 6 speed trans is very bad,particularly from 50,000 miles upwards.
Avoid this one..

Whatever auto you get it won't last like a manual trans. The very nature of them these days means they wear quicker than the old days.
They're all fixable, but most always it's expensive.

[WaspsNest]

redvictor said:

Amazing info..

My good God man, that's the kind of info I was needing. Cold hard facts from the fingers of a human who knows what he's doing.

Difficult one now though. Looks like I'm either
a) Going to spend every mile in an auto waiting for a nasty warning light
b) Going to have to upgrade the ankle of my left foot to deal with some hard work in the coming years.

Thank you for taking the time to respond, especially in referance to my list of preferred metal.
If anyone else has anything, feel free - but this has given me some food for thought.

Nice one PH.

[redvictor]

WaspsNest said:

My good God man, that's the kind of info I was needing. Cold hard facts from the fingers of a human who knows what he's doing.

Difficult one now though. Looks like I'm either
a) Going to spend every mile in an auto waiting for a nasty warning light
b) Going to have to upgrade the ankle of my left foot to deal with some hard work in the coming years.

Thank you for taking the time to respond, especially in referance to my list of preferred metal.
If anyone else has anything, feel free - but this has given me some food for thought.

Nice one PH.

No problem.
If you want an auto and would like a bit of confidence,either get a low mileage model,or go Japanese.
I see very few Lexus's and Toyota's in the shop.

[Herman Toothrot]

I've a an old (2000) Audi A6 2.7TT (250bhp/250lbs) it's on 120,000 miles, occasionally when booting it the gear change feels like slack is geting taken up thn bang and it goes like a manual when side stepping the clutch on launching - it's done this occasionally for the last 20,000 miles had the fluid changed 10,000 miles ago. Does this sound like it may suddenly go bang?

[anonymous-user]

If you want a reliable autobox get yourself one that's widely sold in the US market. Anything fitted RWD from GM, Ford, BMW, Merc or Lexus should be absolutely fine.

If someone's been ragging the car then, yes, an autobox may eventually fail. Otherwise all you might want to think about is a purely precautionary fluid change around 100,000 miles.

How do you rag an auto?

• Full throttle shifting
• Putting it in reverse while still rolling forwards
• Using manual downshifts instead of the brakes
• Overheating it

PS Use the handbrake.

[B'stard Child]

redvictor said:

In order worst is first.


BMW
Citroen
Merc.

All modern transmissions are failed mostly by their electronics.
They also fail via the trans cooler allowing water into the trans.

snip

Whatever auto you get it won't last like a manual trans. The very nature of them these days means they wear quicker than the old days.
They're all fixable, but most always it's expensive.

Andy what's your viewpoint on fluid degradation ie changing transmission fluid on sealed for life boxes?

[redvictor]

B'stard Child said:

Andy what's your viewpoint on fluid degradation ie changing transmission fluid on sealed for life boxes?

Like anything that sees heat, fluid loses some of it's properties in use.
I don't think it does any harm to change the fluid in sealed for life transmissions. The additive package the oil has is renewed, and sometimes the "shift feel" the trans had originally returns. Sometimes it doesn't though.
And remember that the converter will still retain the old oil, so you only really change 2/3rd's of the oil in reality.

[Monkeylegend]

redvictor said:

And remember that the converter will still retain the old oil, so you only really change 2/3rd's of the oil in reality.

Not necessarily the case. Old oil can be flushed out of the torque converter with new oil if done properly and some torque converters have drain plugs, so virtually all the old oil can be replaced.

My last 2 Mercs did over 310k miles each on the original 5g gearboxes with no issues whatsoever. I had the oil and filters changed approx every 80k miles and that was it. Treat them with respect and they will look after you.

[B'stard Child]

redvictor said:

B'stard Child said:

Andy what's your viewpoint on fluid degradation ie changing transmission fluid on sealed for life boxes?

Like anything that sees heat, fluid loses some of it's properties in use.
I don't think it does any harm to change the fluid in sealed for life transmissions. The additive package the oil has is renewed, and sometimes the "shift feel" the trans had originally returns. Sometimes it doesn't though.
And remember that the converter will still retain the old oil, so you only really change 2/3rd's of the oil in reality.

Thanks Andy - I've often noticed the shift improvement after even "partial" chnages my question was becuase it gets a bad press, I belive because in some cases it's done as a fix for a dying transmission and if a transmission has issues it's not going to fix itself with a change of fluid.

Changing fluid and filter is what I've done numerous times and never had a problem as a result

With the cost of a transmission rebuild (labour and parts) I'd rather prevent with a smallish up front cost an issue from being caused by poor fluid condition at higher mileages

Thanks for your comments

[redvictor]

Monkeylegend said:

Not necessarily the case. Old oil can be flushed out of the torque converter with new oil if done properly and some torque converters have drain plugs, so virtually all the old oil can be replaced.

My last 2 Mercs did over 310k miles each on the original 5g gearboxes with no issues whatsoever. I had the oil and filters changed approx every 80k miles and that was it. Treat them with respect and they will look after you.

I can count on the fingers of one hand the converters that have drain plugs.
I can also tell you that not even the greatest flushing machines in the world can get all the oil out of a converter.By their design it's not possible.
I have seen more than 2 mercs,working and owning a trans shop that has been around for over 30 years, and they do fail regularly.

Edited by redvictor on Tuesday 22 January 22:17

[redvictor]

B'stard Child said:

Thanks Andy - I've often noticed the shift improvement after even "partial" chnages my question was becuase it gets a bad press, I belive because in some cases it's done as a fix for a dying transmission and if a transmission has issues it's not going to fix itself with a change of fluid.

Changing fluid and filter is what I've done numerous times and never had a problem as a result

With the cost of a transmission rebuild (labour and parts) I'd rather prevent with a smallish up front cost an issue from being caused by poor fluid condition at higher mileages

Thanks for your comments

Yes, i get calls all the time for me to change the oil and filter on a trans. The first thing i ask is "what is wrong with it?"
95% of the time there is a fault that someone has told them would be fixed by changing the oil and filter.
Certainly the modern trans with sealed for life oil benefits more from an oil change than the old non electric trans.That is just because the additives in modern oil are used extensively, and the PWM shift style of modern transmissions rely on additives to stop bump or slide changes.

[anonymous-user]

redvictor said:

The first thing i ask is "what is wrong with it?"
95% of the time there is a fault that someone has told them would be fixed by changing the oil and filter.

That's one of the curious PH fictions, that a knackered transmission can be fixed with new fluid. Waste of money.

Also, it's far from clear to me what people hope to achieve by changing just the fluid. The filter/screen needs to be changed as well, if only to get a good look and see what bits of material may be lodged in it. (For the uninitiated, it's nothing like an engine oil filter. More like a fine sieve which you can look at). So you don't need a drain plug because you're going to be removing the oil pan in any event.

American proverb: "With modern fluids, if the fluid's knackered it's quite likely the transmission is knackered".

Having said that, a precautionary fluid change around 10 years/100,000 miles only costs about 10% of a transmission rebuild so may be seen as cheap insurance!

[Monkeylegend]

redvictor said:

Monkeylegend said:

Not necessarily the case. Old oil can be flushed out of the torque converter with new oil if done properly and some torque converters have drain plugs, so virtually all the old oil can be replaced.

My last 2 Mercs did over 310k miles each on the original 5g gearboxes with no issues whatsoever. I had the oil and filters changed approx every 80k miles and that was it. Treat them with respect and they will look after you.

I can count on the fingers of one hand the converters that have drain plugs.
I can also tell you that not even the greatest flushing machines in the world can get all the oil out of a converter.By their design it's not possible.
I have seen more than 2 mercs,working and owning a trans shop that has been around for over 30 years, and they do fail regularly.

Edited by redvictor on Tuesday 22 January 22:17

Had mine changed yesterday complete with drain plug on the converter. Flushing/draining removes enough old oil to not make a difference.

As with anything mechanical correct servicing will go a long way to eliminating unexpected failures.

Just offering an alternative viewpoint to the OP based on my experience, albeit only with Mercedes and the 5g box. Looked after it is very robust and good for mega high miles.

[Dog Star]

Just out of interest - Redvictor - what's your opinion on the potential future and reliability of these 7 and 8 speed auto boxes that the likes of BMW and Merc are punting out?

My SLK has a 7 speed box, and while it's mighty nice I am pretty certain that these are going to be giving people some pretty enormous bills some time in their (out of warranty) futures...

[Ari]

5 USA said:

How do you rag an auto?

• Full throttle shifting
• Putting it in reverse while still rolling forwards
• Using manual downshifts instead of the brakes
• Overheating it

PS Use the handbrake.

Using the paddles on a paddle-shift auto is "ragging it"? Why do they fit them then if it's inadvisable to use them?

I often use mine to dial in a downshift or two on a long hill rather than cook the brakes all the way down. Likewise to pre-select a lower gear prior to an overtake rather than hitting the throttle and waiting for it to shift down two or three gears before it goes. Am I really "ragging it"?

Likewise full throttle redline shifts, not that I use full throttle often, seem quick and smooth, with no thumps, bangs, or any sense of "ragging" the transmission.

Not disagreeing, just genuinely curious because I regard myself as having good mechanical sympathy, so if I'm doing it wrong it's good to know.