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

I was listening to a chatty radio show this evening and someone mentioned that he knew someone who put 10 of deisel in with the petrol on every fourth fill-up. He swore it prolonged the life of his engines - and sure enough, his car has so far lasted 30 years....
Just thought I'd pass it on... and listen out for your comments.
Rich
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Rich wrote:

There are plenty of 30 year old cars around, some of them with very high mileages.
The diesel will act as a lubricant to the fuel system and the valves. Modern petrol (read anything post ~1970) is well lubricated - a measured amount of larger hydrocarbons (a lot like diesel) is added to the petrol to act as a lubricant.
Adding diesel to your petrol is totally unnecessary. In addition, adding that much diesel to a tank of petrol (10 = 1/3-1/4 tank?) will make the engine run like crap.

Bored, eh?
--
Grunff

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Well, the guy in question was an old farmer IIRC. He was probably a bit behind the times! Thanks for setting the record straight.
But what about Redex? It was once the in-thing to ask for a a couple of squirts every time you filled up, but no-one seems to bother any more. Perhaps it too is redundant for the same reasons you mentioned?
Rich
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Rich wrote:

This explains a lot. I know many farmers...

That was a looong time ago. Like in the 60s.

Same thing - valve lubricant (and bores to some extent). Won't make any difference with modern petrol.
--
Grunff

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I'm not so sure about that, on a 30 year old engine that is, lead was the upper cylinder lubricant in those days and many a valves life depended on it, current engine technology is such that lead is not required.
A mid '70's engine might well last longer if Redex is used, even with LRP.
This discussion would be more at home in the classic car group !
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:::Jerry:::: wrote:

There is a big difference berween the role played by lead and that played by hydrocarbon lubricants.
The purpose of the lead was twofold: 1. It reduced knocking 2. It formed a coating on the valves + seats, and prevented the valves from welding to the seats, thereby causing valve seat recession.
Hydrocarbon lubricants act to lubricate the valve stem/guide, and the piston/bore.

If it's an iron cylinder head, unless it has hard seat inserts it needs either leaded or LRP with an alternative additive, otherwise the head will only last a few thousand miles.
--
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the
on
LRP.
A far to simplistic explanation, and what the head is made out of is irrelevant.
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:::Jerry:::: wrote:

Only if you have no understanding whatsoever of the mechanism involved in valve seat recession! Have you been taking lessons from IMM? You're starting to sound an awful lot like him.
--
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It is when you fail to understand that what the head casting is made out of is irrelevant to the problem.

The same is far more true of yourself in this respect.
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The word you are grasping for is "too" with two O's.
The material the head is made of is very relevant. Iron heads without seat inserts won't last on unleaded. Aluminium heads must have seat inserts by definition because a valve can't run on aluminium. Whether those inserts are high enough quality to run unleaded is another matter.
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was
depended
with
needs
are
As I said, what the head is made out of is irrelevant, what maters is what the seats etc. are made out of. Thank you for, in a roundabout fashion, agreeing with me !
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LRP.
It's usually aluminium heads that have the real problems. Lancia and Fiat heads from the 70s/80s simply won't survive on modern fuels at all. Have tried all the additives and none work that well.
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Again, it's not what the head is made out of that matters, some V8 Rover lumps (all aluminium) will run quite happily on non leaded petrol (and have done for years) - others will last less than 6k. What matter is what types and grades of metal are used for components such as valves, seats, guides etc.
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Shouldn't be. Ally heads have all got valve seat inserts, and these are by nature rather better (harder) steel than cast iron heads without inserts.
The very worst engines for suffering valve problems with unleaded are the BMC A and B series which have low grade cast iron heads and siamese exhaust valve ports on cylinders 2&3.
--
*The modem is the message *

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

needs
Depends on how good Italian steel is :-)
There was a place called Eurosports near Cambridge who experimented with this and I think got about 50% success rate but I've got several Italian cars in the barn with no way of powering them.
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Having machined some of those heads I'm fairly sure the inserts are often only cast iron rather than steel which is why the problem with unleaded occurs.
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People use BP Ultimate petrol now.
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IMM wrote:

There is very little difference between different brands of petrol sold in the UK. Very little indeed. Many people seem to be able to convince themselves that they can 'feel the difference', but it would never stand up to a double-blind test.
--
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The Ultimate types of petrol have added detergents. They keep your engine clean. Some do give a small ump in power.
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I believe even standard unleaded has added detergents. BP Ultimate is just a higher octane petrol. Unless your engine requires that octane of fuel I don't believe there is any real benefit in using it.
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