How to prolong the life of your petrol-engined car!

Rob Morley wrote:

I was waiting for IMM to go for that argument... (in the give him enough rope kind of way ;-)
The heat capacity may or may not be an issue. It will depend on if the oil reaches the same temperature as the "hot bits". If it does then Prevost's theory of exchanges would dictate that the oil can experience no further nett gain in heat. In this circumstance the higher SHC oil will allow marginally more heat to be moved (as would a higher flow rate). If however (as I expect to be the case) the oil does not reach the same temperature as the hottest parts of the engine that it comes into contact with then the difference in SHC becomes far less significant.
--
Cheers,

John.

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Surely you were really waiting for dIMM to show his erudition by saying that specific heat capacity was not really an issue but Thermal Conductivity was. Or perhaps not. :-)
--
Roger

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says...

Mineral oils deteriorate quite rapidly, and loose their heat absorbing capabilities, far quicker than synthetics ever do.
So once again...an win, win situation.
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It also makes no mention of whether the engine had sensible oil changes before needing overhaul. Cars used for short journeys have always needed much more frequent changes than the norm. Although you might have to look carefully in the service book to find this out. 'Classic' cars tend to be very well looked after by caring owners.
--
*Bills travel through the mail at twice the speed of cheques *

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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<snip>
disbelieves
And marketing speak, you don't NEED synthetic oils, otherwise 70 percent of all the engines used in road vehicles ever build would seize.
I'm not arguing that *high performance* engines don't need synthetic oils, just that the majority of road going cars don't and it's marketing that have told the mass motoring public that they need synthetic oils.
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I think the only reply is:-
<snip rubbish>
--
*Strip mining prevents forest fires.

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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Unless your engine is 30 years old, in which case synthetic oils will piss out past every oil seal and cork gasket they can find.
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Well, the engine is probably the least of your worries on a 30 year old car. Most will have serious rot problems long before the engine gives up - and even a totally clapped engine can be made like new for a fraction of the cost of fixing rust.
And the trouble with these 'my engine has lasted X miles because of Y' is that there is no control data to substantiate it.
Everyone searches for the elixir of life - for themselves, or their cars. Some will be convinced that a spoon of honey or whatever results in them living to 100, while others might say it's a pint of cider. And neither can be proved - or really disproved.
Our US cousins seem to think changing the engine oil every 3000 miles results in long engine life, but seem very reluctant to pay for other fluids in the car to be changed regularly - even although this is a service requrement, and might actually save larger repair bills.
All adding diesel to petrol might achieve for the good is upper cylinder lubrication - and there are better products to do this. The down side is that it will lower the octane rating of the petrol and possibly cause higher localised combustion temperatures on a high efficiency engine - and cause piston or valve damage.
--
*If I worked as much as others, I would do as little as they *

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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