Editing Talk:2478: Alien Visitors 2

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::Although lead was originally added to gas in order to improve efficiency, it was retained in order to reduce refining expense.  After refining crude oil, you get gasoline at a variety of octanes.  The different octanes are blended to produce what you pay for (e.g. 87 for regular, 93 for premium).  Lead is an octane-boosting additive, allowing manufacturers to ship sub-standard gas (that is a little below the rated octane), adding lead to bring it up to standard.  Without lead, you need to blend in a higher proportion of higher-octane gas in order to get the required octane rating.  Which is why, back when lead was being phased out, unleaded gas cost more than leaded.  The effect of lead reducing engine knock is simply a result of the gas having a higher octane rating.  High octane gas without lead (e.g. premium) has the same effect.
 
::Although lead was originally added to gas in order to improve efficiency, it was retained in order to reduce refining expense.  After refining crude oil, you get gasoline at a variety of octanes.  The different octanes are blended to produce what you pay for (e.g. 87 for regular, 93 for premium).  Lead is an octane-boosting additive, allowing manufacturers to ship sub-standard gas (that is a little below the rated octane), adding lead to bring it up to standard.  Without lead, you need to blend in a higher proportion of higher-octane gas in order to get the required octane rating.  Which is why, back when lead was being phased out, unleaded gas cost more than leaded.  The effect of lead reducing engine knock is simply a result of the gas having a higher octane rating.  High octane gas without lead (e.g. premium) has the same effect.
  
::Another interesting side point is that computer-controlled refineries have effectively reduced the quality of gas you get at the pump.  There are serious legal penalties for selling gas with an octane rating below what is labeled, but no penalties for being higher.  Back when refineries were not computer controlled, they were not precise enough to produce the exact blend required, so they would always err a little higher (e.g. selling 88 octane labeled as 87).  But with modern systems, they can sell exactly what's labeled, so consumers don't get any free bonus octane anymore. [[User:Shamino|Shamino]] ([[User talk:Shamino|talk]]) 16:22, 19 June 2021 (UTC)
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::Another interesting side point is that computer-controlled refineries have effectively reduced the quality of gas you get at the pump.  There are serious legal penalties for selling gas with an octane rating below what is labeled, but no penalties for being higher.  Back when refineries were not computer controlled, they were not precise enough to produce the exact blend required, so they would always err a little higher (e.g. selling 88 octane labeled as 87).  But with modern systems, they can sell exactly what's labeled, so consumers don't get any free bonus octane anymore.[[User:Shamino|Shamino]] ([[User talk:Shamino|talk]]) 16:22, 19 June 2021 (UTC)
  
 
:: Leaded gasoline doesn't just provide anti-knock capability, in older cars, the lead gradually accumulates around the valve seats and serves to soften the impact of the valve as it snaps shut.  Modern cars have both anti-knock sensors and hardened valve seats - so you don't need it anymore.  My 1960 Mini needs leaded gas because of the valve-seat issue - and as a result I have to use a lead additive for about one in five tankfuls of gas.  Fortunately, that car is mostly a "garage queen" and is only driven to local car shows and such.  I atone for this by driving a Tesla as my main vehicle! [[User:SteveBaker|SteveBaker]] ([[User talk:SteveBaker|talk]]) 16:06, 21 June 2021 (UTC)
 
:: Leaded gasoline doesn't just provide anti-knock capability, in older cars, the lead gradually accumulates around the valve seats and serves to soften the impact of the valve as it snaps shut.  Modern cars have both anti-knock sensors and hardened valve seats - so you don't need it anymore.  My 1960 Mini needs leaded gas because of the valve-seat issue - and as a result I have to use a lead additive for about one in five tankfuls of gas.  Fortunately, that car is mostly a "garage queen" and is only driven to local car shows and such.  I atone for this by driving a Tesla as my main vehicle! [[User:SteveBaker|SteveBaker]] ([[User talk:SteveBaker|talk]]) 16:06, 21 June 2021 (UTC)

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