On 29/04/2022 14:24, Andrew wrote:
> On 29/04/2022 14:00, Clive Arthur wrote:
>> On 26/04/2022 16:23, jon wrote:
>>
>> <snipped>
>>>
>>> Is synthetic oil better for your car's engine than conventional oil?
>>> Yes. Although conventional oil provides adequate lubrication, it doesn't
>>> compete with synthetic oil's overall engine protection and performance.
>>
>> Plagiarism abounds...
>>
>> https://www.caranddriver.com/research/a32879214/synthetic-oil/
>>
>> https://www.mobil.com/en/lubricants/for-personal-vehicles/auto-care/all-about-oil/learn-about-motor-oil/synthetic-oil-vs-conventional-oil
>>
>>
>
> Modern cars are designed to run much hotter than those made 30+ years
> ago. Such high temperatures cannot be withstood by mineral oil and
> hence the need for synthetic or semi-synthetic oils.
>
> If your car needs synthetic oil then you must use it. If your
> doesn't need synthetic oil don't waste money (twice as expensive)
> on it.

In the scheme of things the cost is small.

I used to skimp on cheap oils believing that it was best to change the
oil and filter but now convinced that wear in engines was accelerated.
Just my gut feeling. I now use Fully Synthetic oil without fail.

I also note that most service intervals are very much extended. One
vehicle it's 20,000 or 2 years. 5-30W Fully Synthetic low ash oil is
recommended.

On 25/04/2022 21:25, newshound wrote:
> On 25/04/2022 16:53, Martin Brown wrote:
>> On 25/04/2022 15:29, R D S wrote:
>>> My car was due a service last year but it had only done 4k miles
>>> since the one 12 months prior so I didn't bother.
>>> It's coming up to another 12 months and has done fewer than 1k
>>> further miles.
>>>
>>> I read that oil shouldn't be left in the car year after year,
>>> opinions on that if you will.
>>
>> If you leave it in for long enough then the oil filter casing will
>> rust away from the outside!
>
> Why? Pressed steel sumps never did, even though much of the paint flaked
> off in fifteen years or so. I have never seen significant corrosion on
> an oil filter.

Funnily enough, my wife's 17 year old Matiz has just failed its MOT
today - one of the failures being a corroded sump! It's the first time
I've ever come across it and, by pure chance, it happened to be at the
same time as this thread.

On 29/04/2022 14:24, Andrew wrote:
> On 29/04/2022 14:00, Clive Arthur wrote:
>> On 26/04/2022 16:23, jon wrote:
>>
>> <snipped>
>>>
>>> Is synthetic oil better for your car's engine than conventional oil?
>>> Yes. Although conventional oil provides adequate lubrication, it doesn't
>>> compete with synthetic oil's overall engine protection and performance.
>>
>> Plagiarism abounds...
>>
>> https://www.caranddriver.com/research/a32879214/synthetic-oil/
>>
>> https://www.mobil.com/en/lubricants/for-personal-vehicles/auto-care/all-about-oil/learn-about-motor-oil/synthetic-oil-vs-conventional-oil
>>
>>
>
> Modern cars are designed to run much hotter than those made 30+ years
> ago. Such high temperatures cannot be withstood by mineral oil and
> hence the need for synthetic or semi-synthetic oils.

Yes. I was used to thermostats opening at 82 to 87 °C and testing them
in a pan of hot water. I wanted to test my current car's thermostat and
found that it doesn't even start to open until 105 °C, so I'd need to
use cooking oil or something similar, which is in short supply at the
moment!

> If your car needs synthetic oil then you must use it. If your
> doesn't need synthetic oil don't waste money (twice as expensive)
> on it.

And if your car needs semi-synthetic oil, which is often little cheaper
than fully-synthetic?

On 29/04/2022 21:52, Steve Walker wrote:
> On 25/04/2022 21:25, newshound wrote:
>> On 25/04/2022 16:53, Martin Brown wrote:
>>> On 25/04/2022 15:29, R D S wrote:
>>>> My car was due a service last year but it had only done 4k miles
>>>> since the one 12 months prior so I didn't bother.
>>>> It's coming up to another 12 months and has done fewer than 1k
>>>> further miles.
>>>>
>>>> I read that oil shouldn't be left in the car year after year,
>>>> opinions on that if you will.
>>>
>>> If you leave it in for long enough then the oil filter casing will
>>> rust away from the outside!
>>
>> Why? Pressed steel sumps never did, even though much of the paint
>> flaked off in fifteen years or so. I have never seen significant
>> corrosion on an oil filter.
>
> Funnily enough, my wife's 17 year old Matiz has just failed its MOT
> today - one of the failures being a corroded sump! It's the first time
> I've ever come across it and, by pure chance, it happened to be at the
> same time as this thread.

Never heard of that before, and after some googling it implies the sump
is in imminent failure.

Major oil leaks are now a fail. I have been advised to jet wash the
underneath. I took the under-tray off and gave everything a good clean.
And of the course the under-tray.

On 29/04/2022 22:04, Steve Walker wrote:

> And if your car needs semi-synthetic oil, which is often little cheaper
> than fully-synthetic?

RTFM. The manufacturer knows what your engine needs.#

Using the wrong oil is a bad as running a car and doing a high
mileage for 2 or 3 years without an oil change, as one of my
neighbours does.

On 01/05/2022 15:44, Andrew wrote:
> On 29/04/2022 22:04, Steve Walker wrote:
>
>> And if your car needs semi-synthetic oil, which is often little
>> cheaper than fully-synthetic?
>
> RTFM. The manufacturer knows what your engine needs.#
>
> Using the wrong oil is a bad as running a car and doing a high
> mileage for 2 or 3 years without an oil change, as one of my
> neighbours does.

The point is that, from what I have read before, for those designed for
plain mineral oil not only is synthetic a waste, but it can actually be
damaging, but for those requiring semi-synthetic, fully synthetic is
usually fine and may allow longer between changes.

On Mon, 02 May 2022 05:29:35 +1000, Steve Walker
<steve@walker-family.me.uk> wrote:

> On 01/05/2022 15:44, Andrew wrote:
>> On 29/04/2022 22:04, Steve Walker wrote:
>>
>>> And if your car needs semi-synthetic oil, which is often little
>>> cheaper than fully-synthetic?
>> RTFM. The manufacturer knows what your engine needs.#
>> Using the wrong oil is a bad as running a car and doing a high
>> mileage for 2 or 3 years without an oil change, as one of my
>> neighbours does.

> The point is that, from what I have read before, for those designed for
> plain mineral oil not only is synthetic a waste, but it can actually be
> damaging,

How does it sometimes damage the engine ?

> but for those requiring semi-synthetic,

I am not convinced that any engine does.

> fully synthetic is usually fine and may allow longer between changes.