Just had car serviced at garage, who tell me that they didn't tighten
the sump drain plug up to 30Nm because the 'threads are stretched', and
they didn't want to strip the thread in the sump.

It now appears that the sump may be leaking from the drain plug.
There's oil on the garage floor. The garage say this is normal wear and
tear and have recommended fitting an insert at my cost.

The car has done 105k, and the oil has been changed 12 times including
the latest service.

Surely if the drain plug was refitted correctly each time the threads
would survive more than 12 uses, even though the sump is alloy.

Any views on this please?

On 18/12/10 13:07, nick wrote:
Just had car serviced at garage, who tell me that they didn't tighten
the sump drain plug up to 30Nm because the 'threads are stretched', and
they didn't want to strip the thread in the sump.

It now appears that the sump may be leaking from the drain plug. There's
oil on the garage floor. The garage say this is normal wear and tear and
have recommended fitting an insert at my cost.

The car has done 105k, and the oil has been changed 12 times including
the latest service.

Surely if the drain plug was refitted correctly each time the threads
would survive more than 12 uses, even though the sump is alloy.

Any views on this please?
The sumps are known for wearing (they're alloy) if someone's a bit
hamfisted. They're not always expensive, so it may be cheaper to get a
new one.

On 18/12/10 01:07 PM, nick wrote:
Just had car serviced at garage, who tell me that they didn't tighten
the sump drain plug up to 30Nm because the 'threads are stretched',
and they didn't want to strip the thread in the sump.

It now appears that the sump may be leaking from the drain plug.
There's oil on the garage floor. The garage say this is normal wear
and tear and have recommended fitting an insert at my cost.

The car has done 105k, and the oil has been changed 12 times including
the latest service.

Surely if the drain plug was refitted correctly each time the threads
would survive more than 12 uses, even though the sump is alloy.

Any views on this please?
It's doubtful if the plug has ever been tightened correctly i.e. using a
torque wrench. Changing the oil in vehicles is pretty much a "lower
order" job in a garage and could have been "entrusted" to near enough
anybody virtually any time it has been done. I have heard many persons
of experience, who should have known better, state that they can tighten
things to given degrees of tightness just on the "feel" - this belief is
most unreliable and largely erroneous, but you can bet your bottom
dollar that the plug has been refitted most of the time using precisely
this "by guess and by God" means.

I believe that VW garages (mine at least) use the oil extraction through
the dipstick hole method (by vacuum), as it's quicker. So it may be that
some of the early "wear" on the threads has been avoided because it will
most likely has been serviced by VW, at least initially.

I sometimes doubt if they are fitted using a correctly set torque
wrench, even during initial assembly, because the first time I took mine
out, on my Mk4 Golf, it seemed far tighter than it should have been. I
always use a torque wrench to tighten my sump plug but normally "chicken
out" before 30Nm is reached, for the precise reason that it is an alloy
sump.

If it has been tightened injudiciously then 12 tightenings is quite
enough to strip, not stretch, the threads. This is what has happened to
your sump, at some point in it's life.

Some people are real butchers and it's difficult to define their
motives, or to detect any logic in their actions. A friend if mine had
an Audi A3, same sump material and same sump plug as yours, fitted in a
three year old vehicle. Someone had rounded off the sump plug to such a
degree that it needed mole grips to remove it! Cost of a new replacement
plug 90p!!!!! Where's the logic in that?

Another man I met had his wheel-nuts replaced so tightly by air-gun in a
tyre-shop/ garage that the studs sheared in service, whilst on a
motorway, causing the death of his 12 month old son.

I have had two consecutive demonstrations of total incompetence at tyre
specialists when attempting to have tracking reset after fitting new
track rods ends. They unlocked my temporary adjustment and would have
sent me out on the road with the track rod free to totally unscrew. Two
tyre specialists, same day, one of them a national chain.

I could go on with many more personal experiences, but I think you get
the picture.

I'm not saying the last man to touch your plug is to blame. He was maybe
the poor unfortunate sod that was at the end of a series of carelessness
and finally, in conscience, had to report it. Either way you'll have a
hell of a job to prove negligence and get them to pay.

If you take your car into a garage, it's totally pot-luck whether you
get a skilled man or a clueless gorilla, with many who don't care as
long as you get off the forecourt. The reputation of the motor repair
industry isn't totally undeserved. If you find a reliable place, stick
to it. Even better, if at all poss, DIY

On 19/12/2010 12:07 AM, nick wrote:
Just had car serviced at garage, who tell me that they didn't tighten
the sump drain plug up to 30Nm because the 'threads are stretched', and
they didn't want to strip the thread in the sump.

It now appears that the sump may be leaking from the drain plug. There's
oil on the garage floor. The garage say this is normal wear and tear and
have recommended fitting an insert at my cost.

The car has done 105k, and the oil has been changed 12 times including
the latest service.

Surely if the drain plug was refitted correctly each time the threads
would survive more than 12 uses, even though the sump is alloy.

Any views on this please?


Funny how the garage knew that the threads had stretched and that it
needed an insert. Wonder when they discovered that? Although its not
uncommon for this to happen.

They should have repaired it there and then and charged you for the
insert not for another service oil etc. If it were me and a thread was
dickey then I would have changed it and not left the car in a state
where the plug is leaking oil or eventually fall out, leading to major
repairs.

Myself I would not return to this garage because they are not looking
after your interests only theirs in verbally covering a problem which
they should have fixed.

It you get an insert then its better and cheaper than a new sump option.

On 18/12/10 13:07, nick wrote:
Just had car serviced at garage, who tell me that they didn't tighten
the sump drain plug up to 30Nm because the 'threads are stretched', and
they didn't want to strip the thread in the sump.

It now appears that the sump may be leaking from the drain plug. There's
oil on the garage floor. The garage say this is normal wear and tear and
have recommended fitting an insert at my cost.

The car has done 105k, and the oil has been changed 12 times including
the latest service.

Surely if the drain plug was refitted correctly each time the threads
would survive more than 12 uses, even though the sump is alloy.

Any views on this please?

@Chris, Tobias, Rob, many thanks. All interesting stuff.

Have also been told that helicoils are often fitted as standard on
commercial vehicles in this application.

Will be getting an insert fitted.

On 20/12/2010 10:12 PM, nick wrote:
On 18/12/10 13:07, nick wrote:
Just had car serviced at garage, who tell me that they didn't tighten
the sump drain plug up to 30Nm because the 'threads are stretched', and
they didn't want to strip the thread in the sump.

It now appears that the sump may be leaking from the drain plug. There's
oil on the garage floor. The garage say this is normal wear and tear and
have recommended fitting an insert at my cost.

The car has done 105k, and the oil has been changed 12 times including
the latest service.

Surely if the drain plug was refitted correctly each time the threads
would survive more than 12 uses, even though the sump is alloy.

Any views on this please?

@Chris, Tobias, Rob, many thanks. All interesting stuff.

Have also been told that helicoils are often fitted as standard on
commercial vehicles in this application.

Will be getting an insert fitted.

Yes that's correct. very common for small 6mm to have inserts.