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Lead additive

Started by genecado, April 21, 2017, 09:45:36 PM

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genecado

Hi I have a 1969 Cadillac Coupe de Ville with 39,000 miles. I always use premium gas. My question is do I need to use a lead additive when I put gas in? Thanks Gene

The Tassie Devil(le)

I would be using a lead additive just as a precaution.

Especially without knowing the condition of the valve seats.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

genecado

Thanks Bruce for the advice.

Julien Abrahams

Yes, you need the lead additive if you are not 100% that the valve seats have been replaced by hardened valve seats. Only the cars that use unleaded fuel from the factory (I believe this was introduced somewhere in the mid seventies) can use the unleaded gas from today. I use an additive in all my old cars.
Caution: always use the same additive. I am not sure, but I've heard from others that mixing additives from different brands can cause a chemical reaction in the gas tank. Although it might be complete nonsense, I decided that I did not want to find out the hard way and always buy the same additive.
1954 Cadillac series 62
1967 Cadillac Sedan De Ville HT
1969 Austin Healey Sprite
1979 Opel Kadett

The Tassie Devil(le)

The '71 and on were designed for Unleaded.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

TJ Hopland

You rarely see or hear about valve seat issues in the 472-500 engines.   One reason is they don't tend to get pushed real hard like they would have if they came in say a Charger or Camaro.    The other reason is I suspect Cadillac used higher nickel castings than your typical Ford or Chev motor so even if they got pushed hard (or didn't have lead) they would wear better. 

I think even in 69 the Cadillac manuals said you could run the new 'low lead' fuels.
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Bobby B

Quote from: genecado on April 21, 2017, 09:45:36 PM
Hi I have a 1969 Cadillac Coupe de Ville with 39,000 miles. I always use premium gas. My question is do I need to use a lead additive when I put gas in? Thanks Gene

Gene,
I've never, ever added lead in any of my cars and they're all pre-73. Have pulled many heads and have never seen problems. But then again, I don't drive like a Cowboy.....
                              Bobby
1947 Cadillac Series 62 Convertible Coupe
1968 Mustang Convertible
1973 Mustang Convertible
1969 Jaguar E-Type Roadster
1971 Datsun 240Z
1979 H-D FLH

35-709

Agree, have never used the stuff in any of the '60s Cadillacs (4) I have owned over the years and have never seen the need to do so.   
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

"Cadillac Kid" Greg Surfas 15364

In 1963 the Engineers at Cadillac (they had their own engineering division then) knew that to meet the pending polution regulations gasoline was going to have to have the lead removed.  Everything from 1965 on was designed to operate on unleaded gas and all provisions were made in materials and construction of the motors to do so.  The major drawback of using unleaded gosoline in your car will be the lack of lead deposits on the spark plugs and the cleaner cylinders and valves.
My '66 went several hundred thousand miles without ever tasting lead and since I have a heavy foot it was driven as hard as any Camero or Charger.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

David Greenburg

Back in the day, (at least the '60's), Amoco sold lead free gas, although my childhood recollection is that it was high octane.  So maybe lead is not that critical as long as the octane is "up there."
David Greenburg
'60 Eldorado Seville
'61 Fleetwood Sixty Special

Carl Fielding

The Kid is a leadfoot. So am I. David is 100% right about octane in the old 10:1 and 10.5:1 compression engines. I had a '70 CDV which I drove to L.A. once , and gave it a treat of 100 or 110 octane gasoline. There were a sufficient amount of stations where you could get that juice. Expensive , at a time when pump gas was under a buck , this stuff was $5 ! But I'm here to tell you , that '70 and my foot sure liked the treat ! DO NOT PUSH YOUR HIGH COMPRESSION CADS HARD ON MODERN 91 - 93 OCTANE PUMP GASOLINE !!! Detonation occurs before you can hear knock. Knock , or "pinging" is not detonation. It is called SEVERE DETONATION. Back off that throttle. Hmmmm , is it deja vu ? Seems I have said this before. I don't know , but I guess it was worth repeating anyway. Did I mention that you could get gasoline up to 129 octane back then ? Probably still can. How else could those multi-billionaires scoot about in their 13:1 "antique" racing Ferraris and the like ? I never had to look into the price those fortunate few had to pay for 129. Speed kills. Enjoy it only in apropriate places and conditions.  - CC

genecado

I want to thank everybody for your opinions. I have heard that using unleaded gas is ok as long as you don't push your engine hard.

35-709

Like marine service or racing.
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

"Cadillac Kid" Greg Surfas 15364

Seem to be missing the point.  Tetra Ethyl Lead was added to gasoline to increase the octane rating.  When lead was slated to be removed from motor fuel, other octane enhancements were developed.  I run VP MS-109 in my quarter mile cadillac.  It is unleaded, and as the name implies is 109 Octane. Only $11.50 per gallon, so it is mixed 50/50 with 93 octane Chevron.  No Lead, no knock.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-