I came across something interesting:

In every source I have seen so far, it says that unleaded petrol can be used
in Minis made after 1989, or in minis with hardened valve seats.

I found a list of engine serial numbers that are compatible with unleaded
petrol, but my engine serial number looks nothing like the serial numbers in
that list (perhaps I am looking in the wrong place - The model in question
is a 1988 Austin Mini City 998 Automatic)

However - and this is the interesting bit - it says on the back of the Mini
manual that came with the car that it drives on unleaded petrol, so I
decided to give it a go. I have been driving on unleaded without lead
replacement additive for a few weeks, and I can't say I notice any
difference.

Is my mini a freak occurrence of an 1988 car that drives fine on unleaded
petrol, or were the sources I found on the net inaccurate?

HJ

It may also be a reconditioned engine from someone other than Rover. Many
reconditioners will use their own numbering.

--
Rgds
Steve
steve (AT) dsnclassics (DOT) co.uk
www.dsnclassics.co.uk

"Steve" <mininews (AT) netcomuk (DOT) co.uk> wrote

Well it may say unleaded on the handbook, but if your Mini is indeed of 1988
vintage, I'd say the manual is intended for a later model. Have a look on
the inside front page near the bottom, there's usually a printing date
there.

Trouble is your Mini may well appear to run happily on unleaded even if it
doesn't have hardened valve inserts, but eventually (or sooner if it gets
heavy motorway use) the engine is going to suffer.

I know a lot of Mini folk use Shell Optimax petrol (unleaded too) as this
has a higher octane the same as old 4 star, but you still need to use an
additive.

Taffy

I was speaking to a generally respected mini specialist here in Perth who
insists that running minis on unleaded is fine even without hardened seats
or lead-replacement fuel additives. He said he has rebuilt 'countless' mini
engines over the last several years and has not done anything to
unleaded-proof them and hasn't had a single one back with problems from
using unleaded fuel

We've been doing this in North America for about 20 years. As long as
you make adjustments for the lower octane rating it's not a big
problem.

Cheers,

Kelley

On Wed, 30 Jul 2003 23:56:54 +0800, "Geoff"
<geoffandkatrina (AT) hotmail (DOT) com> wrote:

Kelley Mascher <mascherk (AT) comcast (DOT) net> wrote

The A-Series engine is particularly prone to valve seat recession,
this is why it was the chosen engine when MIRA were testing lead
substitutes.

I have used minis without hardened valve seats on unleaded with
seemingly no problems, but only if it was an old hack. I certainly
wouldn't do it with an engine that I'd spent money on or cared about
its life expectancy.