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Discussion Starter #1
I wonder how is to use unleaded benzin in non cathalyzed cars?
IS that problem or not?
Do you need to pour any aditive from time to time?
 

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The only cars that suffer from unleaded are those without hardened valve seats from the factory. Tetrathyl lead protected them; without it, they can be worn away by the valves. In those cases an additive will slow, but not stop, the wear. The only real solution is to install hardened valve seats.
 

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Oh wow, I used to have to put lead additive into my 1971 Jeep back in the 90's, I forgot about that. Sorry Mother Earth:oops:
 

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When I was young, you'd find lead in the crankcase. After many miles, at the bottom of the sludge on the bottom of oilpans, there was a layer of gray paste; the lead.
 

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Jim,

My dad is an ex Saab mechanic as well, he used to echo your comments about never seeing older mechanics so he found alternate employment and deterred me from that profession.
 

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Discussion Starter #7
Jim,

My dad is an ex Saab mechanic as well, he used to echo your comments about never seeing older mechanics so he found alternate employment and deterred me from that profession.
Well I met the other day an old mechanic with almost 90 years old, so..., you never knows
 

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Discussion Starter #9
The only cars that suffer from unleaded are those without hardened valve seats from the factory. Tetrathyl lead protected them; without it, they can be worn away by the valves. In those cases an additive will slow, but not stop, the wear. The only real solution is to install hardened valve seats.
The question is if our pre-catalized cars pre88 do they have hardened valve seats from the factory? In other forums they said that our 900 engines has sodium filled valves and this protect the valves against knocking using unleaded benzin.

Can anyone clarify this thing?
 

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C900 with H engine accept unleaded gasoline.
 

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By law, all cars sold in the US had hardened valve seats by 1973.
 

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Pretty sure the rest of the world followed pretty quickly - if not for legal reasons, simply for economies of scale. No point in building heads with hardened seats for some trims in some markets and not just doing them all.
 
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