I read a letter from a chemist about 12 months ago, in a classic car mag,
which said that its exactly the high levels of aromatics that attack the
seals melt - as Bernard describes.
However, it also said that from 1/1/2000, European Union regulations stated
that unleaded must not contain any higher levels of aromatics than leaded
fuel. So in theory, if you live in the Netherlands, your standard unleaded
shouldn't do this kind of damage to the old rubber)
(but this regulation doesn't apply to "lead replacement petrol", which
still melts seals - allegedly)
Neil
At 07:41 Tuesday 09/01/01, Bernard Robbins wrote:
>Personally I think unleaded fuel is an improvement over the leaded. My only
>real gripe is the petrol companies in NZ buy unleaded fuel with very high
>quantities of aromatics (benzene, xylene, tolulene etc) which evaporate
>lowering the octane of the fuel. One has to be careful where one fills up,
>because if the petrol station tanks are getting empty, the octane may be
>lower than what it should be and on the high compression PI cars this can
>be a real pain. The other down side to the aromatics is they are fairly
>carcenogenic which is a bit of a worry to those living in smoggy areas.
>
>Since the change, the car exhaust system lasts longer. With leaded fuel, I
>would have to change the rear muffler at least once a year (the leaded fuel
>is full of wonderful scavenging by-products like sulphuric acid which
>doesn't do the exhaust much good!).
>
>As far as the engine valves seats, the general advice seems to be to run on
>unleaded with a suitable additive (Valvemaster is the most common brand
>here in NZ). I have had a couple of problems with the valve master as a
>major component is kerosene which fouls the plugs if doing a lot of round
>town running. There is another brand (whose name evades me) which is
>basically a pill which one drops into the tank. This seems to burn a lot
>cleaner than valvemaster.
>
>I have not been able to convert my PI to unleaded valves and seats due to
>the large size of the valves. As I understand it, the later cars
>(CRxxxx)had smaller valves and can be re-machined with no problems. The
>earlier cars (CPxxxx) had larger valves and as a consequence, it is
>difficult to fit the valve seats reliably. The problem is that due to the
>lack of metal, the interference fit of the valves can fail (leading to very
>bad things happening to the internals of ones engine).
>
>Sorry this has been a bit long winded, but I hope it is helpful.
>
>Regards
>
>Bernard Robbins
>71 2500PI
>73 TR6 PI
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