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.
There are plenty of 30 year old cars around, some of them with very high
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.
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?
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 !
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
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.
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.
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
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 email@example.com London SW
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.
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.
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.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.