Lead additives in fuel????

Everyone assumes from hearing it enough that lead's purpose was a lubricant. This is completely false. Lead serves no purpose as a lubricant or have any benefits as far a cushining the valve seats. Lead simply increases the octane rating of the fuel.

The big problem here is that most people don't understand what "octane" is. By definition, octane is an additive to fuel that slows it's burn rate. What does this mean?

When fuel is ignited in a cylinder, the "explosion" causes extreme pressure forcing the piston down. If the pressure increase is high enough it will cause the fuel on the outside of the wall "flame" to self ignite causing a severe secondary shoch wave known a detonation. This secondary shock wave is enough to destroy the engine. Since the beginning of the internal combustion engine, detonation has been a problem and after years of testing, lead was discovered to increase the octane rating economically eliminating detonation.

Economists protested against the use of lead and scientists developed new fuels that had sufficiently high enough octane ratings without the use of lead. Through this chemical process, octane levels as high as 104 can be produced and for race engines higher octane levels are needed still today and these levels can only be reached by adding lead additives.

Go to any of your search engines and do searches on octane and compression ratios and you will find many other articles supporting this and the article from Ray,IN that was in a previous post (read section 4.6). Thanks Ray for your time spent finding the article.

So after all this, stay away from lead additives unless you have a high performance pulling tractor and keep in mind that if you add anything to the fuel for whatever purpose you are leaning out the fuel mixture causing higher internal cylinder temperatures therefor reducing the life of the engine.

• Gasoline FAQ

So, a tractor needs a vlave job every 5000 - 10,000 hours. Costs about $500.

If you waste time (can you tell my opionon on this??? :) with the additives, you _still_ will need to do a valve job every so often. The substitutes seem to cost about $750-1000 over that time.

Now, if you just save your money, and whenever the tractor needs a valve job, use the money for that. Hardened valve seats are put in these days, and do not require the lead. Generally, the low compression & slow rpms of most old farm tractors don't wear all that bad without the lead anyhow.

In my opinion, the lead additives are a waste of money - you are better off just doing the valve job when needed, & save the price of the snake oil.

But, if you feel better about it, or it saves family peace, nothing wrong with using them. Just costs you more...

--->Paul

The H could use a valve job, hasn't had one in my lifetime, the 300 needed one 2 years ago because dad ran it without an air cleaner for a while.

The rest are going strong, I believe the 960 had a valve job 30 years ago. I'm sure I put much more that 150 hours a year on each. I'll pretty much swear to that....

Never put any additive in any of them. I use the lowest-cost CENEX gasoline the bulk truck delivers, I'm not aware of any type of additive they put in it - my gasman talked about it 20 years ago, said they really couldn't find anything that would work but not cause problems in catalitic converters so they really couldn't for liability reasons....

Your miliage must vary. I'm not sure how motor oil would help anyhow, the lead was more of a 'cushion' for the banging valves. Oil would burn up in combustion and not really help?

But I don't mean to take over this whole conversation, I'm just a simple dirt farmer & this is all just my simple opinion! :) I'm not even a very good mechanic, so take my words for what you paid for them. :)

--->Paul

Ethanol runs cooler, slightly less power, and disolves stickiness some. All would be a positive for valves? It is not a lubricant which is a negative, but then neither is most of the 400 compounds of gasoline.

--->Paul

As CNKS said, it comes down to how hard the engine will be worked. If the valves & seats stay below a threshold temperature(the temp varies with the valve and seat alloys) there is no problem. In a normally driven car it doesn't seem to be a problem. In a working truck with the same engine it often is a problem. If you are going to work the tractor like a tractor, I would play it safe and use an additive. If you are just using it to pull wagons and do light duty kinds of jobs, it is not mandatory. Another thing...if your head has replaceable valve seat inserts, the seats are most likely hard enough that an additive is not needed. However, I would confirm that with someone familiar with the particulars of your engine...Al English

Thanks for the compliment. We have all been different places and done different things. When a topic comes up where I might be able to contribute something I jump in.

- The temperatures around the circumference of a non-rotating valve are not uniform. Valve rotators are intended to avoid localized heating of the valves and lower peak temperatures. Surprisingly the link Ray posted claims that rotators can contribute to valve seat erosion in engines designed to run on leaded fuel. I am not an expert on old tractors, but I have seen and worked on a number of them that did not have valve rotators. So apparently it varied from one manufacturer to another.

- White gas is gasoline with no motor fuel additives. The lamp/stove fuel sold today is not gasoline. It is petroleum naphtha, which is a high grade of mineral spirits. The unleaded fuel we buy at the gas station has various additives and is not "white gas". An engine does not benefit from using white gas in lieu of a conventional motor fuel. As I explained in an earlier post, using unleaded fuel in an engine designed for use with lead may or may not lead to valve seat erosion.

- The main difference between a car and an industrial/truck/marine/tractor engine is higher loading, and resulting higher internal operating temperatures. Because of their intended use, truck engines must pass more extreme durability testing than car engines. Cars and light trucks are often equipped with the same engines, but one difference is that the truck engine will be equipped with valves made of a more heat resistant material than will likely be used in a car. If the temperature limits of the materials are not exceeded, lead is not a factor. If the limits are not exceed regularly, the affects will be minimal. However, if the engine is routinely run above the threshold temperature for extended periods of time, the absence of lead will significantly lower valve seat life. Tractors are often worked at high power levels for extended periods of time, which leads to high valve temperatures. So assuming the threshold temperature of the valve/seat materials is being reached, the life of the valve seats will be reduced.

- Provided octane is adequate, the only part of the engine that is potentially benefited by lead is the valve seats. But with the right valve and seat materials, lead is a non-issue. And as you pointed out, lead can foul spark plugs.

I think I address all your questions/comments. But if I missed something let me know...Al English

"in the 1950's and '60's, white gas was indeed unleaded gasoline".....yes it was gasoline, and yes you could use it in an engine. But, it did not contain the many other additives that modify and improve gasoline for use as a motor fuel.

"automotive gasoline would foul the ports in two cycle engines".....lead doesn't foul ports, but 2-cycle engines demand a lot of their spark plugs and ignitions. During the era you site plug fouling in 2-cycle engines was an even bigger problem than today. Running unleaded fuel helped by eliminating lead fouling

"an inch and a half of "gray goop" in the bottom[pan]. These deposits are pure lead".....these deposits are not pure lead, lead would be only a trace element

"lead and "lead additives" actually do more harm than good, that lead is a contaminant rather than a blessing"..... Lead was not a contaminant, it was intentionally added to gasoline to allow higher compression/power. Running engines that need this octane on lower octane fuel requires modifications and/or adjustments that reduce power output. Lead was not, as you seem to suspect, part of some scheme to get-over on the public.

"oil pans, full of oil, actually rusted and pitted from these deposits[lead]".....In most environments coating steel with lead actually helps protect it from corrosion. If lead was the culprit, cars made after 1975 would no longer experience this ongoing problem.

"modern three angle valve jobs".....a three angle valve job will in no way compensate for the absence of lead, as I have previously pointed out, its a temperature/materials issue

Buicks, Super 88 Oliver.....if you have experienced no valveseat problems using unleaded fuel in these engines you are obviously not exceeding the critical temperature for the valve/seat materials. As I tried to explain previously, that is the key. However, just because you haven't had a problem doesn't prove that lead wouldn't prevent seat erosion in another application. And, neither does it prove that lead does "more harm than good", or that lead is "a contaminant rather than a blessing".

Valve rotators.....although the true worth of valve rotators has come under some suspicion in recent years, the article indicated they accelerated seat wear in engines already experiencing seat erosion due to absence of lead. The claim was not that rotators promoted seat wear under "normal" conditions.

If you'd like to respond I'll let you have the last word on the subject. Thanks for keeping me on my toes...Al English