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Discussion Starter #1
i bought a 1962 caddy coupe deville and i don't know what gas i should use, i would assume 93 octane(my area), but do i need a additive for the lead?

picking up car today, need to know soon!!!
 

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You can do a number of things here. First of all, if you are sure that the engine is original and that the valves require lead lubrication there are a number of lead substitue products available at most any parts store.

As far as which octane? I would start with 87 octane and a bottle of octane booster on hand. See how it runs with that, if you get pinging add the booster and next tank full go with 89 and booster on the side. Unless you prefer to run 93 anyway. (We can only get 91 here in CA)
 

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DOH! I forgot to add, why not ask the seller (assuming they are the ones who have been driving the old girl) which grade of gas they've been using?
 

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Discussion Starter #4
Kev said:
DOH! I forgot to add, why not ask the seller (assuming they are the ones who have been driving the old girl) which grade of gas they've been using?
i will, the car was from california so i don't know
 

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IIRC the 390 is a 10.5:1 motor... you can try running 86 by retarding the timing several degrees, then slowly inching it back towards normal. If it pings before you get to full advance, you need to run a fuel with a higher octane rating.
 

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I curious about the octane grades available in other areas. Here in California we can get 87, 89 and 91.

Davesdeville mentioned 86, was that a typo or is that regular grade in NM?
90devilleguy mentioned 93, I've heard of that, I'm jealous!

What is available for mid-grade?
 

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terrible one said:
We have 93 here
Is that all? Just 93? Or do you have regular and mid-grade too?
 

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Discussion Starter #9
Kev said:
I curious about the octane grades available in other areas. Here in California we can get 87, 89 and 91.

Davesdeville mentioned 86, was that a typo or is that regular grade in NM?
90devilleguy mentioned 93, I've heard of that, I'm jealous!

What is available for mid-grade?
mid grade is 89 in mass, and we used to up to last year have 94 octane at sunocos

they still have race fuel at some stations but a very limited amount,plus it's like 10 bucks a gallon i'm told
 

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We have 86,87,89, 91, 93, and 94. In MI we also have racing fuel which is 104 or 107 I think.
 

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86 is regular in NM, we get 86/88/90-91. Thanks to the high altitude of over a mile above sea level...

104 is the highest unleaded fuel readily available (VP.)
 

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I wouldn't worry about the lead additives....just run the lowest octane that you can without it pinging. On a higher compression engine, it may take 93. If it runs fine on 87, run 87.
Like addison_ii in Michigan, in Ohio we have 86-94 for road use gasoline.
 

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Discussion Starter #13
lux hauler said:
I wouldn't worry about the lead additives....just run the lowest octane that you can without it pinging. On a higher compression engine, it may take 93. If it runs fine on 87, run 87.
Like addison_ii in Michigan, in Ohio we have 86-94 for road use gasoline.
well i'm gonna stick with 93 for now since i filled it, 26 gallons tank>>>>>>>>>>>>me :(

then i'll check the timing some time this week, and if it's ok then i'll leave it be if it's not then i'll try some lead additive
 

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Kev, no not just 93. That's the premium.

We've got 86 for regular, 89 for mid grade, and 93 for premium. Guess which one I'll be running...:helpless:
 

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Kev said:
I curious about the octane grades available in other areas. Here in California we can get 87, 89 and 91.

Davesdeville mentioned 86, was that a typo or is that regular grade in NM?
90devilleguy mentioned 93, I've heard of that, I'm jealous!

What is available for mid-grade?
Kev, you can thank CARB (California Air Resources Boars) for your lack of higher octane fuel. I believe it was in 96 or 97 that they determined that swithching from 92 to 91 as the higest standard octane avaliable would cut down on polutants by X ammount of ppm. Other than The Peoples Republic of California and some communist states in the norhteast, Octane avaliability is based on average elevation. In NM, you may have 85 as the lowest octane, and 90 as the highest, but have no fear, becuase the elevation is higher, fuel has a harder time burning anyways so it needs less octane (resistance to burn) than usual. Ran 85 octane in a 97 Chevy lumina 3.1 v6 and got 34 mpg and made it from albequerque to Willams AZ on a tank. Here in TN we have 87/89/93. If you really want some high octane gas in CA, Certain Unocal 76's have the racing gas, you just have to find one, the one my dad ran in riverside, on the way to the desert had it, and most the ones ive stopped at in the desert have it, but im sure with the import race scene there, you could find it at more urban locations too.



-The Cadillac Rancher
a California native
 

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Oh yeah, we are well know here for our 'fruits and nuts'. There are a lot of goofy ideas that govern this state. Never forget though, the old saying; "As California goes, so goes the nation." Enjoy the good stuff while you can boys and girls, it may not be long before you are treated to the same regs as we.

We are the Nation's guinea pigs........
 

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Definately run premium. If the car still has its owners manual, it will probably say that. I know my 1970 owners manual (10:1 compression) says to run premium.

Don't trust the previous owners to know what the car should need. The guy I bought my car from was running 87. Also complained about loss of power under heavy load. Probably because it was pinging. Trust me, this 472 has no trouble hauling 5500# of steel up some really steep hills with the cruise on!

It is not the valves that need to be switched for unleaded, it is the exhaust valve seats in the head. Some have said that Cadillad heads (at least on the 472/500's) are tough enough and do not need lead additive. I still run lead additive in my '70 anyways. It is cheap and will ease my mind untill I get hardened valve seats put in sometime.
 

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Discussion Starter #18
BluEyes said:
Definately run premium. If the car still has its owners manual, it will probably say that. I know my 1970 owners manual (10:1 compression) says to run premium.

Don't trust the previous owners to know what the car should need. The guy I bought my car from was running 87. Also complained about loss of power under heavy load. Probably because it was pinging. Trust me, this 472 has no trouble hauling 5500# of steel up some really steep hills with the cruise on!

It is not the valves that need to be switched for unleaded, it is the exhaust valve seats in the head. Some have said that Cadillad heads (at least on the 472/500's) are tough enough and do not need lead additive. I still run lead additive in my '70 anyways. It is cheap and will ease my mind untill I get hardened valve seats put in sometime.
actually i did get with the car the owner's manual and the service manual for the car and neither say what octane of fuel to use so i'm gonna buy 93 unleaded and just throw some lead additive in there.
 

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I would recommend running premium. It may cost more, but you will be able to run the timing at or near spec and ut will be easier on the engine.

Retarded timing leads to lack of power and higher running temperatures. Along with poorer fuel economy.

If you drive the car in a normal fashion, not hard or pulling a lot of heavy loads, it will be fine without the additive. In Canada we have been without leaded gas since 1990 and I have been running my '70 on premium unleaded (Sunoco 94) since I bought it in '93. I have not had any issues with the engine whatsoever.

, Mike
 

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I ran my 70 Eldorado in the US on Premium. But it has the one and only 500 with that high CR. The later Eldo's 500's came with lower CR.

Here in Holland we have 95/98 and even 98 with lead substitute on the tab. In Germany there is also 91. Though I think in Europe the Octane number is calculated differently than in the states, so I don't think the actual difference is that big.

My 500 has been totally overhauled with harder valve seats, so I don't have to worry about unleaded...

Congrats with your classic Framingham!
 
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