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Default OT Engine oil differences

Hi All

I have an old Audi A4 which consumes a lot of oil and has done for years. MOT test fine and no obvious leaks nor particularly smokey. We have been using 5w30 fully synthetic oil and to be honest given how long a litre of it lasts (around 400 miles for a litre) I can't imagine whatever we put in it would make much difference.

I have looked online and some seem to say to use this oil and some mineral oil. Also, I was wondering if a thicker one would be better (assume 5w40 is thicker?).

Will changing to a synthetic 5w40 or even to mineral oil make any difference?

Any oil / engine buffs out there?

Thanks

Lee.
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On 29/06/2018 19:42, The Natural Philosopher wrote:
On 29/06/18 17:57, wrote:
Hi All

I have an old Audi A4 which consumes a lot of oil and has done for
years. MOT test fine and no obvious leaks nor particularly smokey.Â* We
have been using 5w30 fully synthetic oil and to be honest given how
long a litre of it lasts (around 400 miles for a litre) I can't
imagine whatever we put in it would make much difference.

I have looked online and some seem to say to use this oil and some
mineral oil. Also, I was wondering if a thicker one would be better
(assume 5w40 is thicker?).

Will changing to a synthetic 5w40 or even to mineral oil make any
difference?

Any oil / engine buffs out there?

10/40 prolly work best

But when you get to that stage, you are just getting the last out of te
engine so any old **** will do.

Prolly valve seals or guides gone




Changing to 5-40 won't make much difference. That just changes the range
of viscosity compared to 5-30 over a wider temp range. Look he

https://mechanics.stackexchange.com/...nt-engine-oils

I'd not go to a thicker oil, such as SAE10-30. Chances are you've gunge
in there anyway and the last thing you want is trouble with oil circulation.

You could risk a semi-synthetic oil or bulk buy cheap synthetic.

A litre in 400 miles is a lot. I don't put in a litre in 10k miles! My
Honda CRV (80k miles) didn't need topping up between annual changes.


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Default OT Engine oil differences

Brian Reay Wrote in message:
..

A litre in 400 miles is a lot. I don't put in a litre in 10k miles! My
Honda CRV (80k miles) didn't need topping up between annual changes.


I had an Alfasud that used a litre per 500 miles, from new!
Apparently this was "within normal consumption range" for an Alfa
back then.

Tim
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Default OT Engine oil differences

But all Alphas sound like a bag of bolts from new, so what do you expect?
I had a friend with one and it did indeed rattle all the time.
Brian

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"Tim+" wrote in message
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Brian Reay Wrote in message:
.

A litre in 400 miles is a lot. I don't put in a litre in 10k miles! My
Honda CRV (80k miles) didn't need topping up between annual changes.


I had an Alfasud that used a litre per 500 miles, from new!
Apparently this was "within normal consumption range" for an Alfa
back then.

Tim
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"Brian Gaff" Wrote in message:
But all Alphas sound like a bag of bolts from new, so what do you expect?


The Alfa flat four most definitely did not sound like a "bag of
bolts". One of the best sounding four cylinder engines
around.

Tim

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Default OT Engine oil differences

On Friday, 29 June 2018 17:57:22 UTC+1, wrote:
Hi All

I have an old Audi A4 which consumes a lot of oil and has done for years. MOT test fine and no obvious leaks nor particularly smokey. We have been using 5w30 fully synthetic oil and to be honest given how long a litre of it lasts (around 400 miles for a litre) I can't imagine whatever we put in it would make much difference.

I have looked online and some seem to say to use this oil and some mineral oil. Also, I was wondering if a thicker one would be better (assume 5w40 is thicker?).

Will changing to a synthetic 5w40 or even to mineral oil make any difference?

Any oil / engine buffs out there?

Thanks

Lee.


20/50 is thicker, changing to that can reduce consumption. It's a common tweak on a worn engine, the cost is a fraction more friction, but not enough to notice any difference at idle on an open loop controlled engine.

A litre per 400 miles isn't good, you may want to consider the other dodge of adding a tin or 2 of that treacley oil to the engine oil. Really reduces oil burn.

There is one gotcha with oil consumption: a diesel that burns oil can go into runaway & destroy itself.


NT
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Default OT Engine oil differences

In article ,
wrote:
Hi All


I have an old Audi A4 which consumes a lot of oil and has done for
years. MOT test fine and no obvious leaks nor particularly smokey. We
have been using 5w30 fully synthetic oil and to be honest given how long
a litre of it lasts (around 400 miles for a litre) I can't imagine
whatever we put in it would make much difference.


I have looked online and some seem to say to use this oil and some
mineral oil. Also, I was wondering if a thicker one would be better
(assume 5w40 is thicker?).


Will changing to a synthetic 5w40 or even to mineral oil make any
difference?


Any oil / engine buffs out there?


Thanks


400 miles per litre is higher than you'd expect these days, although once
would have been well within spec for many engines.

Have you checked Ebay etc for a source of the correct oil at the best
price? Your garage doesn't pay anything like the 15 quid or so a litre
they charge you. By buying in bulk.

--
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Default OT Engine oil differences

On Saturday, 30 June 2018 11:15:29 UTC+1, Dave Plowman (News) wrote:
In article ,
wrote:
Hi All


I have an old Audi A4 which consumes a lot of oil and has done for
years. MOT test fine and no obvious leaks nor particularly smokey. We
have been using 5w30 fully synthetic oil and to be honest given how long
a litre of it lasts (around 400 miles for a litre) I can't imagine
whatever we put in it would make much difference.


I have looked online and some seem to say to use this oil and some
mineral oil. Also, I was wondering if a thicker one would be better
(assume 5w40 is thicker?).


Will changing to a synthetic 5w40 or even to mineral oil make any
difference?


Any oil / engine buffs out there?


Thanks


400 miles per litre is higher than you'd expect these days, although once
would have been well within spec for many engines.

Have you checked Ebay etc for a source of the correct oil at the best
price? Your garage doesn't pay anything like the 15 quid or so a litre
they charge you. By buying in bulk.


the 'correct oil' is the wrong stuff for a well worn engine.


NT


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Default OT Engine oil differences

In article ,
wrote:
On Saturday, 30 June 2018 11:15:29 UTC+1, Dave Plowman (News) wrote:
In article ,
wrote:
Hi All


I have an old Audi A4 which consumes a lot of oil and has done for
years. MOT test fine and no obvious leaks nor particularly smokey. We
have been using 5w30 fully synthetic oil and to be honest given how long
a litre of it lasts (around 400 miles for a litre) I can't imagine
whatever we put in it would make much difference.


I have looked online and some seem to say to use this oil and some
mineral oil. Also, I was wondering if a thicker one would be better
(assume 5w40 is thicker?).


Will changing to a synthetic 5w40 or even to mineral oil make any
difference?


Any oil / engine buffs out there?


Thanks


400 miles per litre is higher than you'd expect these days, although once
would have been well within spec for many engines.

Have you checked Ebay etc for a source of the correct oil at the best
price? Your garage doesn't pay anything like the 15 quid or so a litre
they charge you. By buying in bulk.


the 'correct oil' is the wrong stuff for a well worn engine.



400 miles a litre is *not* a badly worn engine. Even more so if it runs
OK. Could be something as simple as valve stem seals failed. And using a
much thicker oil in an attempt to reduce costs may just result in the
engine really wearing out faster.

--
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Dave Plowman London SW
To e-mail, change noise into sound.
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On 30/06/2018 12:39, Dave Plowman (News) wrote:



400 miles a litre is *not* a badly worn engine. Even more so if it runs
OK. Could be something as simple as valve stem seals failed. And using a
much thicker oil in an attempt to reduce costs may just result in the
engine really wearing out faster.


As you almost suggest, the devil is in the detail.

This is what tabby said earlier

"20/50 is thicker, changing to that *can* reduce consumption. It's a
common tweak on a worn engine, the cost is a fraction more friction, but
not enough to notice any difference at idle on an open loop controlled
engine.

A litre per 400 miles isn't good, you *may* want to consider the other
dodge of adding a tin or 2 of that treacley oil to the engine oil.
Really reduces oil burn"

and he's right, that was one of the traditional routes from the days
where bore and ring wear, or valve stem wear, resulted in significant "burn"

As you say, it *could* be failed valve stem seals. No such thing in the
old days, but I've never seen a comparison of how much of the historical
improvement in consumption comes from the introduction of seals, and how
much from improved materials and engineering of piston rings and bores,
plus better anti-wear oil additives.

My academic friends in places like Leicester and Warwick reckoned that
one of the big steps forward was the introduction of plateau honing for
bores. You arrange for the first machining to introduce deep scores (and
high peaks), then you remove the peaks by honing to provide the running
surface for the rings, while the scores provide an oil reservoir which
gets replenished from below. It's certainly remarkable how you no longer
have to "run in" a new engine, or pistons following a rebore like we all
did when I first started rebuilding engines in the 1960's.

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On Saturday, 30 June 2018 16:50:17 UTC+1, newshound wrote:
On 30/06/2018 12:39, Dave Plowman (News) wrote:



400 miles a litre is *not* a badly worn engine. Even more so if it runs
OK. Could be something as simple as valve stem seals failed. And using a
much thicker oil in an attempt to reduce costs may just result in the
engine really wearing out faster.


does it?

As you almost suggest, the devil is in the detail.

This is what tabby said earlier

"20/50 is thicker, changing to that *can* reduce consumption. It's a
common tweak on a worn engine, the cost is a fraction more friction, but
not enough to notice any difference at idle on an open loop controlled
engine.

A litre per 400 miles isn't good, you *may* want to consider the other
dodge of adding a tin or 2 of that treacley oil to the engine oil.
Really reduces oil burn"

and he's right, that was one of the traditional routes from the days
where bore and ring wear, or valve stem wear, resulted in significant "burn"

As you say, it *could* be failed valve stem seals. No such thing in the
old days, but I've never seen a comparison of how much of the historical
improvement in consumption comes from the introduction of seals, and how
much from improved materials and engineering of piston rings and bores,
plus better anti-wear oil additives.

My academic friends in places like Leicester and Warwick reckoned that
one of the big steps forward was the introduction of plateau honing for
bores. You arrange for the first machining to introduce deep scores (and
high peaks), then you remove the peaks by honing to provide the running
surface for the rings, while the scores provide an oil reservoir which
gets replenished from below. It's certainly remarkable how you no longer
have to "run in" a new engine, or pistons following a rebore like we all
did when I first started rebuilding engines in the 1960's.


As you say we can't know from here what the cause is. I remember one where consumption was traced to oil being dumped on the exhaust manifold. When I say 'traced' I mean it all became clear when it caught fire.


NT
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Default OT Engine oil differences

Thanks all for your help. To answer a few questions and add some clarity.

It is a petrol Audi A4 s-line 1.8 turbo which has done 125k miles so likely the engine is a bit worn. It had always used oil but not to the current extent. Besides the cost there is always the hassle of constantly topping it up. When the oil pressure sensor detects you have forgotten to top it up and you are in the middle of nowhere and you realise you forgot to top up the spare can in the boot. All a bit of a PITA.


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In article ,
Jim K wrote:
Istr the official "fully synthetic oil from new" regime has been
implicated in this excessive oil consumption. Something to do
with the piston rings not getting a chance to bed in
properly.


Synthetic oils were developed to extent oil change intervals. If they
stopped piston rings bedding in - which is basically wear - they'd also
stop other bits of the engine ever wearing out.

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On 01/07/2018 12:12, Dave Plowman (News) wrote:
In article ,
Jim K wrote:
Istr the official "fully synthetic oil from new" regime has been
implicated in this excessive oil consumption. Something to do
with the piston rings not getting a chance to bed in
properly.


Synthetic oils were developed to extent oil change intervals. If they
stopped piston rings bedding in - which is basically wear - they'd also
stop other bits of the engine ever wearing out.

The *big* difference with synthetics is that because they don't contain
such a variety of molecules as mineral oils, their oxidation performance
is better. So they last longer at higher temperatures. Bedding in is
influenced by by boundary lubrication. This comes from the anti-wear
additives like ZDDP in either mineral or synthetic lubes. Mineral oils
often have enhanced boundary lube properties because they contain fatty
acids (as impurities) which, if you like, are nature's anti wear
additives. Automotive lubricants (whether mineral or synthetic) are
fairly highly "engineered" to optimise their properties (because the car
manufacturers specify the required performance for a given engine).
Further down the market, the effectiveness of things like 3 in 1 is
almost certainly partly down to the fatty acids. (This product also
contains effective anti-rust additives, which I suspect are responsible
for the distinctive smell, although I have never managed to find anyone
to confirm that).

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