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Lead Additives / Alternates


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I've got very good access to top tier non-ethanol higher octane fuels here in Vancouver. Chevron has a 94 octane non-ethanol and Shell carries a 91 octane, so I make sure to use those in both the 67 Electra and 78 Estate Wagon.  The Electra seems to prefer the 94 octane stuff.  As far as additives go, I don't bother with any lead additives for the 67, but I will put a few ounces of Marvel's Mystery Oil into a tank every once in a while. and I make sure to use an oil with higher zinc levels.    I have read that buick motors in this era have a higher nickel content in the heads so the lead is not required.   I've been running the 67 this way for about 18 years now and it's very happy.

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You should not need lead additives. There are octane boosters that you can use if high-octane pump gas isn't enough for a very high compression engine, but if your car runs without pinging on pump gas, don't waste your money on other things you dump into the tank. Lead isn't and never was added to fuel to "cushion" the valves. It was an octane booster. That nonsense about cushioning the valves was largely made up by the oil companies when leaded fuel was being phased out in the early '70s. Originally they were supposed to eliminate it in 2 or 3 years, but the oil companies started whining about all the poor schmoes whose engines would self-destruct without the cushioning effects of the lead. That was BS, but it was enough to buy them another 5 or 6 years for the changeover.

 

For the most part, additives are designed for one purpose: turn your money into their money. If the engine doesn't ping on pump gas, additives are not needed.

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I'm sure that many of us remember Amoco gasoline back in the day. It was lead-free decades before lead in fuel became an issue. I don't recall any of their competitors warning about how Amoco gasoline would destroy engines because of the lack of lead with its valve "lubricating" or "cushioning" properties. Countless Nail Heads ran on the stuff.

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Detonation happens before the Engine "pings". The term for what is happening when you hear that pinging sound is severe detonation. Detonation can occur at any point of the power stroke. Not good.     -    Carl 

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I think most gasoline GM engines from about 1980 on have knock sensors and if the sensor hears detonation, the computer will retard the timing so the knock goes away. 

 

I also agree with the other comments that unless you are hammering the gas pedal, it is not necessary to use premium gas especially on cars with knock sensors.  Timing is automatically retarded when knocking is detected.

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Yes, but hammering the pedal is so much more fun when the car responds instead of the immediate power loss felt when ping starts and the knock sensor retards the timing!

 

In both the supercharged Buicks I can hear and feel the difference in running high test vs regular. Sure, the engine will protect itself, but its so slow!😧

 

Anyway, the question was lead additive vs no lead additive, not high test vs regular.....

 

I also never use a lead additive. 

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Interesting thing about the knock sensors.  When I was a service rep, I had a car that just did not have any power. It ran ok, and sounded ok, but just no power like it should have.  All of the scanner data looked fine except there seemed to be more retard in the spark advance than "normal"   When we unplugged the knock sensor, we found the problem.  The engine had a bad rod bearing and the knock sensor was retarding the timing enough so we could not hear the knock when the engine was running.

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At the seminar that Denny gave at the Buick Centennial meet, he noted that when GM put out the mandate that all GM engines had to operate on low-lead/lead-free fuel by April, 1971, using induction-hardening of the valve seats, that Buick didn't need that due to their higher-nickel content in their cast iron "mix".  But that they had to DOWNGRADE their metal recipe to induction-harden the valve seats instead.  Which would mean that until April, 1971 engine production, the Buick V-8s would operate just fine on unleaded fuel, sans additives, just as the Nail Heads had done before them.

 

"Lead" was both an octane booster (inexpensive one at that) and a lubricant of softs to decrease valve seat erosion as the valve rotation might happen.

 

For the earlier '70s, Chrysler was year or two later to do the induction hardening of their valve seats, so their recommendation was to use one tank of leaded fuel for every three tanks of fuel.  For 1974, when they started doing the induction hardening of the valve seats, that recommendation vanished in the owner's manuals and such.

 

I found an article in a Chilton "Automotive Industries" magazine, circa 1973, which detailed a durability test that Chrysler did on a 1973 Town & Country wagon, with the full HD trailer package and a 440 V-8.  It had graphics which followed the valve seat recession as the test progressed.  The car & trailer were run on a test track at highway speeds until it wouldn't run any more.  By the end of 12K miles, the exhaust valve seats were non-existent on most cylinders.  Higher loads, even with a cruise rpm of less than 3000rpm, generally.

 

From what I learned from my machine shop operative, years ago, the longevity of "the valve job" relates to valve stem/guide condition.  When the guide and valve stem start to wear, the valve can cock slightly as it goes up and down.  When the valve starts to be a bit cocked when it starts to seat, it might not seat fully, allowing for some exhaust gas leakage around it's perimeter.  Which ends up making a hot spot at that point, which then "melts" that sport on the edge of the valve head, over time.  Obviously, heavy loads and higher combustion temps can accelerate this situation.

 

The induction hardening operation will discolor the metal on the valve seat.  But with a stated depth of .003", it gets ground through with the first valve job.  But it obviously goes a bit deeper than the discoloration or all of those heads would have had vailed valve seats later on, I suspect.  Didn't see that happen, or hear of it either.

 

My recommendation for the "forever" valve job is to use OEM-spec chrome-stem valves with the bronze heli-coil valve guides, along with OEM-spec valve seals ONLY.  Some oil needs to get into the guide, but not too much.  When the guide wears, the valve wobbles and the seal integrity (of most types) degrades, by observation.  The chrome stem/bronze heli-coil is supposed to be the best friction interface available, much better than the normal cast iron guide/chrome stem interface.

 

As for ADDITIVES . . . When the "Real Lead" fuel additive was around, using a whole can in 20 gallons of unleaded fuel would not even get it to the level of the prior low-lead fuels!  Might take THREE cans to get to that level, as I recall.  Lead being a dangerous chemical substance and all of that.

 

I ran across an article on lead-replacement fuel additives in a trailer magazine back in the later '70s, maybe earlier '80s.  It noted that there were two basic types of such additives.  One type was sodium-based and the other was oil-based.  Alemite CD-2 had one that I suspect was sodium-based (which was supposed to be the better type).  I used it without any problems . . . until . . . the sodium stuck an accelerator pump circuit "weight" closed on a Carter ThermoQuad I had on one of my cars.  Took forever to get it to even act like it wanted to start, with no pump shot!  When I took off the accel pump shooter, freed-up the weight, then things worked well again.  End of using that type of fuel additive!  Didn't tell that it worked enough to keep using it.

 

Later on, installing hard seats became a normal part of a valve job on older engines, anyway.  EXCEPT for Buick Nail Heads, due to the prevalence of "striking water" in those cylinder heads.

 

It should be noted that there are OTHER fuel components that serve the same anti-valve-recession functions as the prior tetra-ethyl-lead did.  As the old Amoco fuels obvisouly had in them, back in the '60s.

 

Enjoy!

NTX5467

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