Jump to content

Fuel additives


Dauphinee
 Share

Recommended Posts

Being a newbie I just purchased my first bottle of additive for my car.

The place I purchased it from told me by NY state law he had to say that it is for use on motor vehicles that don't run on the road.

I thought all older vehicles needed the additive.

Is this becoming a growing problem?

Is there a solution to the additive?

What happens if I run without it?

Link to comment
Share on other sites

You don't say what vehicle(s) you have nor the type of additive you purchased...

For the cars I am most familiar with (1930s through 1950s Plymouth L-Head (flathead) six engines) no gasoline additives of any kind are needed.

For other makes and eras of cars, additives of one type or another might be advantageous. But for that you'll have to say what type of car and engine you have and if it has been modified from stock.

It might be a good idea to use an additive to keep gasoline in your tank from deteriorating if you are storing the vehicle for long periods of time. But that is a different matter.

Link to comment
Share on other sites

A little Redex or Marvel Mystery Oil can't hurt. But many old cars need no additives.

The cars that have a potential problem are the high compression OHV engines made between 1955 and 1970. These are made to run on leaded gas which is not available anymore.

You shouldn't need to worry about cars made before 1955 or after 1970.

The only ones that have a real problem are the very high compression high performance models with over 9.5:1 compression. They are the only ones that need lead additives or special fuel.

An engine that has been rebuilt since 1970, probably has the low compression and hardened valves and valve seats installed. The others don't get enough use to burn out the valves.

But if you are concerned, as I said it can't hurt to add a little upper cylinder lube to the gas. Bardahl, Redex, MMM there are several brands to choose from.

Link to comment
Share on other sites

The car is a 1936 Pontiac Deluxe 8.

I don't know if the motor was ever worked over. There have been many previous owners of the car so it would be hard to say if it had ever been touched.

So from what your saying that I shouldn't have to put anything into the gas??

Link to comment
Share on other sites

hi dauphinee, your pontiac straight eight is a low to mid range rpm engine, and the compression ratio is much lower than the engines made after 1955. so even with all new parts, rebuilt engine with zero miles on it, your engine will be fine with today's gasoline, find the gas stations that sell gas without eythanol junk in it. use shell rotella oil for the engine also. charles coker, 1953 pontiac tech advisor.

Link to comment
Share on other sites

The lower the compression ratio the lower the octane. Your car will run best on the lowest octane regular. It was made at a time when gas had very little lead added. Typical octane rating back then was less than 70 compared to 87 for today's regular.

A little upper cylinder oil added to the gas will help prevent wear but is not absolutely necessary.

Link to comment
Share on other sites

I run ATF (automatic transmission fluid) in all of my cars from 1955 to 1979 - some of which are high compression, some aren't, but choose the gas depending on which engine it is. The high compression ones will still ping even with 98 octane, but that is modern gas and there is not too much you can do about it. However, the ATF cleans thr varnish out of the fuel lines and acts as an upper cylinder lubricant/cleaner and will do absolutely no harm. Also doesn't need to be new ATF - you can keep what you take out at oil changes, filter it and put 2 pts in at each full tank.

Link to comment
Share on other sites

I use the green STA-BIL in my 50 F1 since they did away with the last real gas in NY. I also dump a little Marvel Mystery Oil in every once in awhile when I remember.

Link to comment
Share on other sites

Gee another fuel additives thread!

These days we have really three types of fuel additives, each supposedly good for one thing or another. We've been fixated on some sort of fuel additive since the 1950's, maybe earlier, with such things as Wynn's Friction Proof, which supposedly aided in upper engine lubrication. (some chose to use ATF instead) Does this do anything for upper engine lubrication? Probably not considering the fact only a very small amount of oil is introduced with fuel and is burned with that fuel. Some will swear this works, but having put 100s of thousands of miles on cars without upper engine lube of some nature I seriously question the alleged benefit.

With 1974 we had a mandate for unleaded fuels and with it came all sorts of claimed problems with unleaded fuel and engines in vehicles of previous years. Enter the lead substitute additive. But what did/does it really accomplish? Not sure, beyond removing money from one's wallet.

Now we have fuel stabilizers supposedly keeping today's oxygenated fuels from going bad over an extended time in storage or a fuel tank. Do they really work as claimed? Hard to say, but they don't keep oxygenated gas from getting the funky smell old oxygenated gas develops after months of being in a fuel tank in a car or a gas can. Do they preserve the octane rating of the fuel? Good question. Never seen any claims indicating such. But I do know a 10.0:1 engine will run without pinging on "old" gas. It just makes the exhaust smell like hell.

If we owners of pre fuel injected vehicles need an additive of any kind it would be one that would kill those injector cleaners in today's gasoline that are capable of destroying rubber components in our carburetors and mechanical fuel pump type fuel systems, eating softer casting metals of times past, and with ethanol eat tanks and steel lines. Truthfully, having driven millions of miles in gasoline fueled automobiles since 1956 the only fuel modification I have ever found to unequivocally work on a typical normally aspirated car engine is the water/alcohol injection system that was popular in the early 1980's.

Jim

Edited by Jim_Edwards (see edit history)
Link to comment
Share on other sites

What are the differences/advantages of green Sta-Bil (marine) over red?

The green is suppose to keep the alcohol based gas from going bad as fast. The red helps but the green does more according to their website. It costs more but it is more concentrated so it comes out about the same or cheaper.

Link to comment
Share on other sites

I use Sta-Bil red and CD-2 additive in the Judge, just Sta-Bil in anything liable to sit for a while.

Have used both ATF and Marvel Mysery Oil as an additive both for gas and in the oil (ATF is about a 20 wt super high detergent - have used to clean parts before) but mainly for engines with problems (noisy lifters, etc).

Edited by padgett (see edit history)
Link to comment
Share on other sites

Rislone in the oil & Sta-bil in the tank has been a winning combo in my cars..

Probably similar to my plan: Lucas Upper Cylinder Lube & Fuel Injection Cleaner - about 5/6 oz. per 25 gallons or so and Sta-bil in the tank.

The Lucas product works well and seems to make my 496" Volvo-Penta powered boat run like a sewing machine. Same can be said of my muscle cars and the GMC that hauls any/all of em.

My 'Cowboy windage' feeling is that I'm getting better mileage too.

Use Sta-bil in your outdoor power equipment fuel too. It does not get turned over as quickly as vehicle fuel and try to find pure gas for them (boats too).

See you on the show field or the water - trouble free so far...!!

Link to comment
Share on other sites

The Lucas oil additive for gasoline will decrease the octane rating which can cause detonation and lean the fuel mixture. So you will get better gas mileage but less power. I found this out when I added way too much to my tank. I could go for days at 50 mph.

If you use oil additive in High performance engines you should use High octane fuel or an octane booster additive.

In antique car's such as the 1936 Pontiac the oil additives can bring the fuel to a mixture that is closer to what the car was designed for. But it will not remove the additives in the fuel that will damage your new old stock pump diaphram.

Link to comment
Share on other sites

The lead additive that has been banned from our gas did 3 things. it raised the octane and lubricated the valve seats and stems. this is the reason cars and trucks from 1975 have hardened valve seats. I have rebuilt many older engines that had the valves especially the exhaust sunk as much as 1/4 inch in to the head. This is moor apt to happen on engines that are run hard , especially trucks. YES the Bell additives are a He!! of an additive

Edited by ac63corvette (see edit history)
Link to comment
Share on other sites

The lead additive that has been banned from our gas did 3 things. it raised the octane and lubricated the valve seats and stems. this is the reason cars and trucks from 1975 have hardened valve seats. I have rebuilt many older engines that had the valves especially the exhaust sunk as much as 1/4 inch in to the head. This is moor apt to happen on engines that are run hard , especially trucks. YES the Bell additives are a He!! of an additive

The original poster has a 36 Pontiac they are worried about. Back in that day you had to pay a premium to "fill it with Ethyl" and standard gas did not have lead. Their fuel additive requirements are quite different than those who have, say, 1960s high performance V8 engines.

Looking at the Standard Catalog, their compression ratio is either 6.2:1 or 6.5:1 depending on which series car they have. For that they probably need maybe 80 octane. So they don't need an octane boost.

Valve seat recession can be an issue on engines where the valve seat is ground directly in to the casting and the engine is being driven hard for long periods of time. Truck engines, cars pulling trailers at high speeds, etc. It seems unlikely that a 1936 anything needs to worry about that.

So the additive(s) that you might feel are required for a 63 Corvette are unlikely to be needed for the original poster's car.

My personal feeling is all the Dauphinee needs to do is assure that the rubber parts in their fuel system have been replaced with ones that are not damaged by modern fuel additives like ethanol and then just fill the tank with as cheap a gas as they can find when they run low.

Link to comment
Share on other sites

From research I have done on available octane vs compression ratio over the years, the rule is the octane should look like the compression ratio. In other words if you have 6.5:1 compression you need 65 octane gas.

Naturally this is not an exact rule but it is pretty close. In other words, for the above car the ideal gas would be 60 to 70 octane. Today's cheapest regular at 87 octane is plenty high, in fact the car might well run better with some kerosene or diesel fuel added to the gas to lower the octane.

http://books.google.ca/books?id=3toDAAAAMBAJ&pg=PA1&lpg=PA1&dq=1936+octane+gas&source=bl&ots=mTEUn5zP8p&sig=-qU8V7T511aJ1NibwLJEs2f5qN8&hl=en&ei=pvfbTaqSJov5sgaik6XODg&sa=X&oi=book_result&ct=result&resnum=3&ved=0CCcQ6AEwAg#v=onepage&q=1936%20octane%20gas&f=false

Here is an article from a 1937 magazine about new super power gas. If you read down far enough it says in the last 15 years, car engines have increased in efficiency 23% thanks to the improvement of hi test fuel from 60 to 80 octane. Your Pontiac was probably made to run on regular gas which was 60 or 65.

Edited by Rusty_OToole (see edit history)
Link to comment
Share on other sites

... in fact the car might well run better with some kerosene or diesel fuel added to the gas to lower the octane.

Huh? Since when does "too high" an octane cause issues? Octane is a measure of resistance to knock, are you saying that older engine should have some knock? Last I heard knock was bad for any engine.

Now if you are trying to reduce the fuel volatility to address possible issues with the fuel vaporizing in places you don't want like the fuel pump or hoses, that is a different issue...

Link to comment
Share on other sites

Actually, octane isn't a resistance to knock, but rather a resistance to ignition. Higher octane fuel takes more energy to cause it to explode, which is why it controls knock--only the spark is hot enough to make it explode. The weaker ignition systems on older cars will still ignite high octane fuel, of course, but they'll have an easier time of it with lower octane. I'm sure there's theory about flame propagation and the energy required to overcome the resistance at the spark plug and things like that which make Rusty's point valid.

That said, I don't think fuel additives are required and the fear over valve seat recession is more wives' tale than fact on low compression old cars. Sta-Bil might be a good idea for storage, but I don't use it in cars that I drive often.

Link to comment
Share on other sites

Many ways to phrase it. Octane rating measures how much a fuel can be compressed before it spontaneously ignites or "diesels" or "knocks". The greater the percentage of certain parts of the chemical "octane" the more a fuel can be compressed before igniting.

Link to comment
Share on other sites

Great thread, so for clarification on lead additives. For instance, I have a 1940 Plymouth with a 1952 L-Head 6 in it. I do not need to purchase lead additive?

All the Plymouth L-6 engines from 1933 through the end of production (1959 for cars, 1972 for industrial applications) came from the factory with hardened exhaust valve seat inserts. No need to add lead to your gas unless you want the remember the good old days when your spark plugs could get lead fouling and you want to make your wallet a little lighter.

Link to comment
Share on other sites

I agree with some of the thoughts here, but not all. Most oil additives, not so much help. Oil additives, in days of old, were the unscoupulous car sellers favorite tool to dope an engine for a short time. Fuel additives can be of value. Two reasons: vapor lock( fuel starvation) & volatility of fuel making it deteriorate faster. Alcohol is the major culprit, some thing cars of 25 years ago did not endure. Kerosene ( et, al) to 10% ethanol gasoline, in theory, should lower the flash point. geting the precise mix is another matter. Stabil was famous for landscape tools to preserve through the season, as a film of stabil "oil" lays across the surface of gasoline blocking evaporation. Evaporation is some thing ethanol does very well. Again, theory says that it should work in cars the same way. Thoughts?

Link to comment
Share on other sites

There has been a lot of discussion of octane being "too high" for low compression engines. Some have reported their engines run smoother and cooler, are less prone to vapor lock, and produce more power, on a mix of gas and diesel or kerosene. This mainly applies to very low compression engines of the twenties and thirties, 4.5:1 to 6:1 compression engines.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...