Re: switching to synthetic oils

On Sun, 07 Nov 2004 18:14:30 +0000, Mr.Nice.
<mr.nice@*nospam*clara.co.uk> wrote:

>I read in a book that synthetic oils reduce engine wear to virtually
>nil (got to be a good thing).
>
>My 1984 110 has done around 230k miles (2.5 n/a diesel engine).
>When I first got it I put 15w40 mineral oil in it. at the last oil
>change I tried 20w50 mineral oil (API=SF/CC).
>
>Worth noting that in around 5000 miles on the 20w50 the engine has not
>noticably used any oil.
>
>My question is...
>Would it be a good idea to switch to a thinner fully (or semi)
>synthetic oil?
>

NO.

If you switch to a synthetic oil you'll be asking for trouble. Not
only is the engine not designed for it, but it will do an excellent
job of flushing out the engine, and it will rattle, clunk and clank
from then on. The dirt and sludge will be fed round the engine,
causing premature wear and tear on almost everything, finally
accumulating in the filter which will clog up. Low oil pressure bekons
due to unclogged oilways and clogged filters. Valve lifters will
probably get clogged as well, resulting in noisy tappets...The list
goes on.

The engine has been run in and beyoned on Mineral, then you should
keep on using mineral. You might consider a mineral oil with Diesel
Additives, and 15w40 is probably better for a diesel than 20w50,
although there's not a great deal of difference in the grade.

You could switch to semi-synthetic, but it's not reccomended for the
same reasons, and the engine neither needs it or is designed for it. I
would never consider switching on an old engine, unless the engine has
been completely stripped, cleaned, re-worked and rebuilt. And even
then, there's no advantage as the engine does not need it. A good
quality Classic 20w50 with detergent is the best in this case.

Alex

"Alex" <[email protected]> wrote in message
news:[email protected]...
> On Sun, 07 Nov 2004 18:14:30 +0000, Mr.Nice.
> <mr.nice@*nospam*clara.co.uk> wrote:
>
>>I read in a book that synthetic oils reduce engine wear to virtually
>>nil (got to be a good thing).
>>
>>My 1984 110 has done around 230k miles (2.5 n/a diesel engine).
>>When I first got it I put 15w40 mineral oil in it. at the last oil
>>change I tried 20w50 mineral oil (API=SF/CC).
>>
>>Worth noting that in around 5000 miles on the 20w50 the engine has not
>>noticably used any oil.
>>
>>My question is...
>>Would it be a good idea to switch to a thinner fully (or semi)
>>synthetic oil?
>>
>
> NO.
>
> If you switch to a synthetic oil you'll be asking for trouble. Not
> only is the engine not designed for it, but it will do an excellent
> job of flushing out the engine, and it will rattle, clunk and clank
> from then on. The dirt and sludge will be fed round the engine,
> causing premature wear and tear on almost everything, finally
> accumulating in the filter which will clog up. Low oil pressure bekons
> due to unclogged oilways and clogged filters. Valve lifters will
> probably get clogged as well, resulting in noisy tappets...The list
> goes on.
>
> The engine has been run in and beyoned on Mineral, then you should
> keep on using mineral. You might consider a mineral oil with Diesel
> Additives,

This is compulsory. This engine will not function long without diesel high
detergent oil. Any oil which has a current diesel rating will be high
detergent and higher than many synthetic oils without a diesel rating so
this nonsense about loosening crap is just that, crap, in this application.



and 15w40 is probably better for a diesel than 20w50,
> although there's not a great deal of difference in the grade.
>
> You could switch to semi-synthetic, but it's not reccomended for the
> same reasons, and the engine neither needs it or is designed for it. I
> would never consider switching on an old engine, unless the engine has
> been completely stripped, cleaned, re-worked and rebuilt. And even
> then, there's no advantage as the engine does not need it. A good
> quality Classic 20w50 with detergent is the best in this case.
>
> Alex

Whether an oil is synthetic or not is totally irrelevant when talking of
this engine. A synthetic oil will not provide a single advantage point over
a diesel specific oil or a multifleet oil with dual rating such as commonly
available API SL/CH4.
I do not know of any oil that will magically perform better than this in an
engine which is just so dirty.

Huw

"Mr.Nice." <mr.nice@*nospam*clara.co.uk> wrote in message
news[email protected]...
> On Mon, 8 Nov 2004 10:26:58 -0000, "Huw"
> <hedydd[nospam]@tiscali.co.uk> wrote:
>
>>
>>"Alex" <[email protected]> wrote in message
>>news:[email protected]...
>>> On Sun, 07 Nov 2004 18:14:30 +0000, Mr.Nice.
>>> <mr.nice@*nospam*clara.co.uk> wrote:
>>>
>>>>I read in a book that synthetic oils reduce engine wear to virtually
>>>>nil (got to be a good thing).
>>>>
>>>>My 1984 110 has done around 230k miles (2.5 n/a diesel engine).
>>>>When I first got it I put 15w40 mineral oil in it. at the last oil
>>>>change I tried 20w50 mineral oil (API=SF/CC).
>>>>
>>>>Worth noting that in around 5000 miles on the 20w50 the engine has not
>>>>noticably used any oil.
>>>>
>>>>My question is...
>>>>Would it be a good idea to switch to a thinner fully (or semi)
>>>>synthetic oil?
>>>>
>>>
>>> NO.
>>>
>>> If you switch to a synthetic oil you'll be asking for trouble. Not
>>> only is the engine not designed for it, but it will do an excellent
>>> job of flushing out the engine, and it will rattle, clunk and clank
>>> from then on. The dirt and sludge will be fed round the engine,
>>> causing premature wear and tear on almost everything, finally
>>> accumulating in the filter which will clog up. Low oil pressure bekons
>>> due to unclogged oilways and clogged filters. Valve lifters will
>>> probably get clogged as well, resulting in noisy tappets...The list
>>> goes on.
>>>
>>> The engine has been run in and beyoned on Mineral, then you should
>>> keep on using mineral. You might consider a mineral oil with Diesel
>>> Additives,
>>
>>This is compulsory. This engine will not function long without diesel high
>>detergent oil. Any oil which has a current diesel rating will be high
>>detergent and higher than many synthetic oils without a diesel rating so
>>this nonsense about loosening crap is just that, crap, in this
>>application.
>>
>>
>>
>>and 15w40 is probably better for a diesel than 20w50,
>
> I know the difference is small but I went for the thicker oil due to
> the mileage of the engine. and it now uses no oil (5000 miles).
> both the haynes and the LR manuals say 14w40 or 10w50 are both ok.
>
> would I really be better with the 15w40? why?
>

I didn't say that, Alex did.
20w/50 should not really be used below 0C ambient. Apart from that there is
nothing wrong with it in your application as long as it meets reasonable
current diesel specific performance standards.

Huw