Gasoline

[Guest]

I am curious about what octane gas anyone owning a pre-1950 automobile uses? I have been told by some to use a low octance gas in my 48 Packard since it has a factory compression ratio of 7 to 1. What do others out there use (and why?)

[Guest]

there is no reason you use any higher octane than the engine needs ,so why spend the extra money? I used to occasionally put 5 gollons of kerosene in my 32 Buick , and it kept down the vapor lock problem , and ran just as good on the mix of 5gal to 15 gal of gas

[Guest Hal Davis (MODEL A HAL)]

The Oldest Guy 2 is absolutely correct! The only purpose of higher octane gasolines is to prevent detonation (pinging) in engines with high compression ratios. If it doesn't ping with 87 (and at 7:1, it shouldn't), then burn 87 in it. I would recommend a good BRAND of gasoline, but not the higher grades unless needed.<P>As a side note: Have you ever wondered what the (R+M)/2 method is that you see on the octane sticker on the gas pump?<P>It is the average of two different methods of figuring octane equivalent. One method is to determine how low an octane an engine can run on, AT IDLE, without pinging. The other is to determine how low an octane an engine can run on, UNDER LOAD. Then they average the two. The problem is, that no one's engine pings at idle. It's the "under load" number that is important. At the pump, you don't know what you're getting. 86 and 88 average to 87, but so do 77 and 97. It's just a hunch, but I think these two numbers are closer together with the better brand names of gasoline. It doesn't matter that your gasoline acts like 97 octane at idle if it acts like 77 octane going up a hill!

[Guest]

Plus we're the only country in the world to measure octane this way so there's a lot of import owners out there putting premium in their tanks when they could be running on regular (regular 87 AKI being 91 RON, so it says "91 octane" and means regular).<P>Cheers,<BR>Bry

[ronbarn]

On a Founders Tour back a few years ago I was driving my '61 Cadillac and ran with a friend in her '54 Buick. We drove exactly the same mileage each day and pulled into the same service station each day to fill up. Every day my fill up would be between $1 to $2 cheaper and she could not figure out how I was getting so much better mileage. I let her stew on this and razzed her a little and finally on the last day told her I was buying 87 and she was always going with the 92.<P>I run 87 in all my cars, even the newer Suburban and have had no problems. As for brand names, a friend drove a gas tanker for an off-name brand here in Alabama and got the tanker filled from the same depot tanks that the brand names used, but normally I also stick with the bigger names.

[ply33]

I believe that the two octane numbers are derived from two separate set of tests in a special single cylinder motor designed specifically for measuring octane. Not from running it in a car at idle and under load.<P>The two tests (Motor and Research) simple use two different set of test cycles. If I recall correctly, the research test cycle will generally give a higher octane rating to the same batch of fuel than the motor test cycle.<P>So, in general MON < MON+RON/2 < RON.<P>A little while back I heard that just after WW2 typical US retail gasoline had an octane rating a bit below 70 (don't know if this was RON or MON). (Probably RON as everyone likes to advertise a higher number.)<P>Also heard that the "76" in Union 76 originally was to promote their 76 octane fuel, higher than most of the competition.<P>Probably the only cars that really need high octane gas are the muscle and sports cars of the late 1950s through the 1960s.

[Guest]

A lot of modern engines require the good stuff too, unfortunately.<P>Cheers,<BR>Bry

[Dave@Moon]

As a hazardous waste inspector for the state, I've been to all of the fuel depots in the Pittsburgh area. With rare exceptions, it's all pretty much the same stuff. The "off brands" generally buy from the majors and operate on a thinner margin. The differences among brands amount to little more than snake oil.<P>One rare exception I found was a small, independant chain (that shall remain nameless) here that for quite some time sold off-spec paint thinner (xylene/tolulene blends) as high-test gas. They're not around anymore, and I don't know of anything like that occurring now. I am always wary off off-brands in areas I don't know as a result. Also if it doesn't smell right (for gas), I don't trust it.

[ply33]

Gas has not smelled "right" for quite some time here in California..... I assume that the modern additives smell different (and worse) than those used decades ago.

[Guest]

There must be a difference in quality. My OBD2 Firebird monitors fuel quality, if it's not up to snuff it retards the timing to protect the engine and throws an SES light.<P>The only times it's done this to me was using generic-branded fuel. Therefore I stick to the major brands for ALL my cars; just because the older cars don't have a sensor doesn't mean they're not suffering.<P>As for octane I run the lowest it'll accept without going below the manufacturer's requirements.<P>Cheers,<BR>Bry

[Dave@Moon]

Tod, what you're smelling is reformulated gas, with MBTE added to increase oxygen content and lower emissions. Unfortunately the stuff is carcinogenic, and mixes with groundwater so that it can't be conventionally removed . I hope you're not one of those guys who still uses fuel to clean parts! <P>It's been banned by the EPA for those reasons and is being gradually phased out starting this year. It'll probably be replaced in your area w/ ethanol (not methanol, which is the real bad news alcahol for fuel systems). Remember gasahol? <P>Some people report problems with ethanol in high compression engines, but it seems to be OK on fuel gaskets and lines. At least my experience w/ it was OK. I drove 40,000 miles in Iowa on gasahol in the early 1980's in a 1960 Falcon with no problems, and none of the people I knew there reported any either.<P>Now for the mandatory 18 postings on how gasahol ruined a thousand cars. <p>[This message has been edited by Dave@Moon (edited 04-26-2000).]

[Guest Hal Davis (MODEL A HAL)]

Tod,<P>You are correct about the special engine that is used to determine octane rating. I did not mean to imply that it was tested in automobiles. I had forgotten what the R and M stood for, and also which was which (been a long time since Thermodynamics). Thanks for the refresher.<P>Bry,<P>You are oh so right about some of the modern cars needing 93. Up until about a year ago, my wife drove an '88 Mustang GT with the 5.0L. It would let you know right away (first hill you tried to climb) that it did not appreciate 89 octane. I don't know what the compression ratio was, but boy would it ping if you didn't use 93!<P>As for brand names: It could just be a coincidence, but we always ran a good brand of gas in the Mustang and had no fuel related problems in 130,000 miles. Some people we know had the same engine in their car, ran the cheapest gas they could find, and had to have the fuel injectors cleaned by the dealer several times while they owned it.<P>

[Dave@Moon]

You don't need a performance car to need 93 octane. The lowly VW Passat and 1990-1994 Subaru Legacies need it, too.

[ply33]

Going back to the original question: For a 1948 vehicle with a 7:1 compression ratio you can use the cheapest (lowest octane) gas you can find. For my 5.5:1 compression ratio 1933 I definitely use the cheapest gas to be found. It will run on anything and the sediment bowl filter does a pretty good job of keeping water out of the carb.<P>For newer cars it is different. My 1991 Jeep pings on 87 but does not need 92, so it gets the 89 octane intermediate grade. (The manual says it will run on 87. Wrong!) Since it has a dreadful time with any water in the gas I always carry a bottle of "dry gas" and generally go to major brand stations where, I hope, they do a better job of keeping their tanks clean.<P>The 1981 Plymouth with a 2.2L engine I had ran okay on 87 but hated the 85 octane I found on visits to Colorado. The 1963 Dodge D200 with a 318 V8 ran great on the cheapest gas I could find.<P>The lowest octane gas that does not ping is all your car needs. Two cars with identical engines could actually need different gas based on driving styles. The engine might be marginal on 87 but since you never push it you never get predetonation (ping). Another driver who pushes it hard or has long grades to pull may not be able to get by on the lower octane.<P>My guess is that most collector cars are not pushed to their limits and can get by with a bit lower octane than they originally specified. Since today's fuel has a higher octane than the fuel of 1950, you can run just about anything in those older cars.<P>Possible exception: Prior to WW1 gasoline had a pretty high octane (result of gasoline being treated as a waste product of the refining process rather than a primary desired product). I understand that some of the carburetors on very early cars were very bad at doing their job and needed pretty good gas to get a runnable mixture.

[Guest]

One thing you need to be aware of when using gasoline containing alcohol. Alcohol is used to cut shellac. We used it for that purpose for years in the mirror manufacturing business.[Old, old process]<BR>In carbs with cork floats used on early cars the cork was coated with shellac to keep it from becoming saturated with gasoline. The alcohol in gas WILL gradually disolve the shellac!!<P>From personal experience. If you used gas tank sealer 20 years ago, it was not at that time impervious to alcohol. We have a Model A with 1/2" of disolved sealer on the bottom of the tank.<P>HV<p>[This message has been edited by hvscotyard (edited 04-27-2000).]

[ronbarn]

I can vouch for HV's concern from first hand experience. I was helping Dave Kolzow start his 1895 Benton Harbor (since donated to the AACA Museum). It is the oldest operating American car and he was showing it for the first time and it just would not start. Turned out he was out of gas. I ran over to my bike trailer and fetched a full gas can. Poured it in, and the car started and ran for about 15 seconds, died, and would not restart. Pulled the carb and sure'nuff, I had used some gasahol and the shellac on the float was gone. Raced to the hardware store, got new shellac, got some real gas, and after about an hour we got the car going. This was an embarassing moment, but the car was repaired quickly and the thrill of seeing the magnificent vehicle was tremendous. Next time you are around Hershey stop in to the Headquarters and take a look.

[Guest]

Having worked in marketing and sales in the oil business years ago, I am always amused at the approaches that companies have used over the years to sell higher octane gas to more motorists. It's correct that octane ratings have crept up over the last 50 or 60 years to accomodate higher compression ratios. You should never use a higher octane than specified for your car. It's a waste of money and actually could shorten engine life. <BR>Having actually loaded far too many gas tankers to count, you would be amazed at the practices within the oil business regarding sources of gasoline, formulation, pricing, etc.

[Guest]

Hal, ~~ I have used the new, alcohol resistant sealer in at least 4 cars with nothing but satisfactory results. I got my first cans of this from Snyder's at least three years ago and have ordered more since.<BR>I don't think they even carry the old stuff anymore, but just be safe and specify alcohol resistent when placing an order. I imagine that any Ford restoration supply house would have it, but I was in Snyders on a Founders tour and got mine while there. <P>Not only does it seal the pinholes, but it seals the fine rust under it. There is NO WAY to get all the rust out, but before coating I recommend putting small sharp rocks or chain into the tank and shaking vigerously and long to break all the rust from the inside of the tank. I have done both. IT WORKS.

[ronbarn]

For a while Bill Hirsch sold the old and the new, but I think he has finally stopped the old. His new gas tank sealer is indeed resistant to alcohol and works great. He ads in Hemmings and other magazines and sells at Hershey. Have used it and am staisfied. Would not put a tank back into a rework, restoration, upgrade, whatever, without coating the tank.

[Guest Hal Davis (MODEL A HAL)]

Since HV brought it up... What about the newer gas tank sealers? Are they alcohol proof? I know a guy who had this problem with an A he had restored only 3-4 years ago. Because of his experience, I had about decided to not seal mine. It does have some rust, but it doesn't leak. I'd rather have to empty some rust out of the sediment bowl and screens than try to get all the sludge out of the bottom of the tank. Can anyone recommend a sealer that is alcohol proof or know of a fool proof way to be sure the gas you're buying has no alcohol?

[Guest Hal Davis (MODEL A HAL)]

Thanks Ron and HV, I feel a little better now. I had seen the stuff this guy had scraped out of the bottom of the tank, and rust seemed like a lot better alternative. I will make sure I get the "new" kind when it comes time. <P>Hal

[Guest]

I recently repaired a fuel tank corrosion problem by cleaning the tank with muriatic acid, and coating with a two-part epoxy product, purchased at a local auto parts store (sorry, I don't remember the name of the product). This has held up well, and I have no more problems with clogged fuel filters. If I remember right. the cost was about $20.00/qt.<BR> <BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by MODEL A HAL:<BR><B>Since HV brought it up... What about the newer gas tank sealers? Are they alcohol proof? I know a guy who had this problem with an A he had restored only 3-4 years ago. Because of his experience, I had about decided to not seal mine. It does have some rust, but it doesn't leak. I'd rather have to empty some rust out of the sediment bowl and screens than try to get all the sludge out of the bottom of the tank. Can anyone recommend a sealer that is alcohol proof or know of a fool proof way to be sure the gas you're buying has no alcohol?</B><HR></BLOCKQUOTE><P>

[Guest]

My 1940 Buick Special owner's manual recommends "regular" grade gasoline, minimum 70 Octane (248 straight-eight).<P>The larger series cars (Century, Roadmaster, Limited) with the 320 engine are advised to use 76 Octane.<P>The lowest-rated octane gas I've seen in recent memory was the Sunoco "Economy" grade, which was 86. <P>I remember Getty used to sell LEADED Regular 88 Octane in the '70's.