Christoph,
Yes, the correct oil filter has an internal check valve that holds the oil
in the engine's passages when the car is not running. As Tony said, the
proper Mahle (make sure it's the correct one, some don't have the valve) or
Bosch (ditto) ones will help. Unfortunately, some filters (Purolator, etc.)
fit on the engine but either do not have the check valve - allowing the oil
to drain into the pan while stopped - or, even worse and common on a certain
Orange filter - the filter media offers too much resistance to the high flow
of oil causing media implosion and the fluffy bits get sucked into the
engine causing blockages in the oil passageways. A search on Audifans or
Audiworld should give you the correct Mahle part number.
The Engine Flush (only did it once) worked for me, but of course, YMMV, etc.
etc. The hydraulic lifters appear to be gummed up causing them to stick.
Of course, any liquid that will remove the sticky stuff around the lifter
will also remove sticky stuff that is sealing the old, dried up gaskets in
the engine. Apparently Synthetic Oil - true stuff like Mobil 1 (not Castrol
Syntec) - will do the same, just not as aggressively. I noticed a huge
increase in leakage when I put the M1 in my old 5000 - turns out that
synthetic also shrinks cork gaskets - such as the ones installed on the
valve covers of old Type 43 Audis.
Wynns seems to work a bit for me - it's on sale every once in a while. If
anything, it makes me feel better knowing I'm doing something to combat the
sound.
Cheers!
Steve Sears
1987 Audi 5kTQ
1980 Audi 5k
1962 and '64 Auto Union DKW Junior deLuxes
(SPAM Blocker NOTE: Remove SHOES to reply)

"Christoph Bollig" <laserpower@gmx.net> wrote in message
news:anqfu09nto8496rvnf7bi4ug5dl5cqgag6@4ax.com...
> Hi again,
>
> Just to make sure I understand this correctly:
>
> > Yes, it's true that it doesn't matter. My '87 5ktq had some noisy
lifters
> > when I got it a few years ago, the switch to synthetic oil and proper
filter
> > (with a check valve) helped somewhat -
>
> Do you mean the oil filter? I didn't know there were any with or
> without check valve.
>
> > I also used an engine flush which
> > helped immensely,
>
> I asked someone at a spares shop today who used to work for Audi/VW.
> He thought an engine flush is not a good idea at such a high mileage
> (220 k km), since it would remove some of the carbon which holds the
> oil in place.
>
> > and I put a can of (IIRC) Wynn's Engine Restore in with
> > every oil fill.
>
> I don't know whether that's available here, will have to check.
>
> Thanks anyway, I will keep you updated.
>
> Christoph
>
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