The Stovebolt Site Forums The Shop Area General Truck Talk Fuel

Not sure about the premium gas around here but I know the lower two grades of gas contain ethanol. Since I'm looking at a '67 GMC 3/4 ton with a 305 V-6, what would be the best way to go as far fuel grade and should a lead substitute be used? Or just not worry about it. I'm leaning a certain way but would like other opinions.

87 octane unleaded will run just fine in it. No need to put the higher grades of fuel in it. I wouldn't be too concerned with the ethanol, either, it's been around in some areas since these trucks were new.

It depends on what you are going to use the truck for. If you are going to do lots of driving at highway speeds , you might consider a lead substitute some times. If you will be driving around town at lower speeds and not a whole lot of miles, I would just use the lower grades of fuel.
The 305 V-6 is a pretty tough engine.
Jim

It's been running for 46 years on, I'll bet, just about anything
that was handy. All these old vehicles run just fine on about
any pump gas. No advantage to putting in high octain fuel
unless you're running high compression ratios.

DG

No need for a lead substitute no matter the driving you're doing. Just use 87 and forget about it.

Some of the substitute stuff will really load up the combustion space deposites. Been there done that.

For me it's the cheapest 87 octane, or occasionally some old crap I drain out of something, haven't feared that, either. A 305 has an advertised 7.75-1 comp ratio, octane rating doesn't matter a lick, run anything that says gasoline.

I used some old fuel?(no idea if alcohol) in my IHC 345, siezed several valves, bent two pushrods. Others have had same results. I stay from unknown old fuel now, not worth it.

I second that. I had the same experience.

Some Marathons have what they call 90 Plus recreational gas which is NON-ethanol. It's good if you're gonna leave it sitting awhile, has a longer shelf life than ethanol gas.

How much extra do they charge for that over regular unleaded?

They charge a good bit more. Currently, reg 87 is 3.19 and the 90 plus is 3.89. I'm just glad to have access to it for the '52 or anything else that sits most of the time, like the mower during winter.

Old fuel is different from ethanol. Now you're talking varnish and all the other nasty things that happen when gas gets old. I wouldn't use that either!

Ethanol itself shouldn't hurt anything, although it does tend to go bad sooner than the old gas used to. If letting it sit for a prolonged period, I would use a stabilizer of some sort.

Boy, I don't know where you guys are buying your gas but my lawn
mowers, riding and push, chain saws, trimmers, Track-Vac yard
vacuum all sit the whole winter with the same gas in them and
they all start and run on last years 87octain 10% just fine.
Got two stationary generators that have fuel that's years old
in them and they start and run just fine. My truck with it's
stock 216 sat from July of last summer till a few weeks ago
with a 1/2 tank of the same type of fuel in it and it started
just fine and I drove it for 20 or thirty miles before I filled
it with fresh fuel.
Don't see how fuel that's a few months old is gonna make a well
maintained engine bend a valve. I can see how trying to run an
engine that has been sitting for years where the oil has turned
to wax and the valves and guides are rusted can bend a push rod.
Easy solution might be take it apart and fix it right before
trying to start it.

Denny Graham
Sandwich, IL

the only thing I have seen the alcohol ruin was the plastic pickup in my weedeater. Other than that I have had no problem. With the exception of getting worse mileage. I had exhaust valve inserts installed because I was planning on running considerably more compression than stock. But in the final analysis, without doing major milling and the associated valve sinking, fiddling with the rocker arm height/valve stem height I couldn't get any better than 7.5:1. So it really wasn't worth it. The PREVIOUS engine ran around 30 years without the hardened seats or leaded gas (at least from the time they stopped producing it) One thing my dad found out kinda by accident, was using premixed 2 stroke oil in all the lawn equipment just as a convenience to avoid having to keep track of which can was which. He has avoided tank rust out and things seem to just work better, along with a friend of his who has a bunch of old stationary engines. Had reported the same thing. May be something to think about if your truck sits for a long time. I haven't done it in years as I use my truck regularly now, but that wasn't always the case.

2 summers ago I had some 12 week old gas in the truck

it turned a rancid honey color and the truck wouldn't run or idle

...pic...

...pic...

rebuilt the carter. cleaned the lines and fuel pump.

So now in the summer when I drive less because of the heat I don't fill er up. Try to keep fresh gas in it. I also add stabilizer in the summer.

I run my 216 on 87 from Sam's Club. Every other fill up or two I put lead substitute in if I remember. I usually top off from a half tank or so. Every oil change I run 4oz of Marvel thru the lines too.

I didn't mean to suggest using old fuel, my point was that you really don't need to worry about what you put in the tank of a 7.75-1 advertised comp engine if it came from a pump in this country marked "gasoline". The old fuel I used wasn't insanely old, anyway, and I didn't burn it in a tight engine. The pictures Dads50 posted are interesting, looks like the Nevada heat spoils it a lot faster than here! I would have thought longer than twelve months from the pictures, much less weeks.

I am also using 87 E10 for everything right now, myself. I've thought about getting some of that 90 at Sunoco for two stroke mix, but haven't really had any problems with the E10 to push me. So far, anyway. I try to run everything every one in a while, no problems as of yet.

Thanks for the replies. It seems around here the gas has caused alot of problems. Just doesn't last very long. That's the only reason I mentioned the premium. I was told it didn't have ethanol in it. Looks like I'll stick with regular. And use a stabilizer when needed.

I pulled an '87 Power Ram out of a Southern Missouri barn last summer. Been sitting there about 10 yrs. Put a new alternator, mechanical fuel pump and battery in, fired her right up and drove 3/4 of a 10yr old tank out on the 2hr drive home with no issues.

If it's fuel injected, any 87 will do, if it has a carb, no ethanol, living by this has saved me alot of headaches imagined or actual. YMMV.

I gotta ask. what difference does having a carb make? I have been using alcohol gas for however long they have bee producing it. It works just fine in the truck, and the mustang...

Google ethanol and carburators, lots of good reads. I purchased my 52 Chevy truck six months ago w/283, Holly 600, don't know what the owner used to fill up with, but since I've had it have decided not to use it in my old truck or lawnmower. Local boaters here prefer to avoid it as well, some will use it with stabil.

When our local Amoco closed it's doors and the local farmers started filling their grain trucks with E10 gas from Casey's, my dad did dozen's, if not hundreds of carb rebuilds, fuel pumps, and tune ups. Since then, he hasn't had very much problems at all. The Ethanol is like a detergent, it clings to the varnish and impurities in the fuel system and brings them out. The ethanol isn't the problem per se'. The problem is that most of the vehicle he was working on, are only used for a couple months out of the year and then brought back out to do work again. After the vehicles have had their year long vacation, the ethanol is waiting their with 30 years of garbage to come back out.

I'm actually and advocate of Ethanol and Ethanol fuels. I used to drive a tanker and I have delivered 100's of thousands of gallons of the stuff. My stations with Ethanol, never had any moisture in the tanks and the tanks were cleaner than the ones with straight gas. I've ran it in everything from weed eaters to my 302 powered boat, without any issues.

Someone earlier mentioned Marathon Gasoline. I would keep away from their 87 octane gas. It is actually a low grade gasoline (84 octane) with Ethanol added to it in order to bring it up to spec. The stuff was super cloudy and smelled funky right from the get go. Other than that, I wouldn't hesitate buying gas from any station or any brand, with or without ethanol.

I don't need to google ethanol and carburetors, I'm living it. The only thing it has affected so far is the fuel pickup in my weedeater. But it has only been about 10 years or so, guess time will tell.

My feeling, non-scientific of course, is there'll be fewer reported problems once the parts market is fully shifted to ethanol compatible rubber parts. It seems to harden traditional rubber diaphragms prematurely, such as in the mechanical fuel pumps and carbs. That's my observation. YMMV

I've got nothing against ethanol per se, it's the manner in which it's been mandated by an agency of non-elected officials leaving marine, motorcycle, collector car, farm, and commercial users, etc. without viable options.

Given time, it'll all settle out and everyone will be happy. Like the oh-my-gosh-no-more-leaded-gas years. Remember that? The sky didn't fall then, and it won't this time either.

I would even mind the no option part, if they would at least tell us what the consequences were. Like the zinc in the oil thing, but I don't know exactly which type of public forum they would/should use to disseminate this type of information....Perhaps large type signs on gas pumps like the ones they use to tell you gasoline is flammable, (no kidding), or the same type of label they put on cigarettes, on oil cans. (you can tell I am getting old, when was the last time they used cans for oil?) It can't really be that hard.

I think the ethanol "problems" are way overhyped in the vintage vehicle hobby, 'urban myths' rattle around endlessly .... the trouble with old rubber formulations is they've been sitting on the shelf for decades, and the trouble with the gas 'going bad' is so many folks don't actually use the vehicles, any gas is volatile and undergoes changes when left sitting for extended periods .... I've been using E10/15 since it first appeared locally, with no problems - some folks have been using it much longer

Bill

had ethanol w/stabil go bad in my chevy II that I foolishly let sit nearly 2 years. had to clean out the brand new gas tank with lacquer thinner, all the rubber lines were swollen and turned into a funky soft gunk. Haven't fired it up yet (have to order new plug wires as I installed different distributor) to see if I have to change fuel pump/rebuild carb. My LTD sat maybe 6 months without moving, it ate up new fuel pump and carb. It attacks rubber if it sits. My mower was running rough, checked fuel lines, they had swollen and soft/gummy. I noticed a new Holley I bought had a tag metal wired to it that said use of any ethanol gas voids any/all warranty.
I don't go to the trouble of hunting ethanol free, but I try to keep things moving more frequently now. I think if moving regularly (maybe weekly), it shouldn't cause issues, seems to be when it sits.
about the zinc, I asked a local machine shop, they felt if your motor had ever been ran with zinc and broken in, it could safely be ran later without any additive. They said same about lead, if it had ever been ran on leaded gas, the valves were coated and likely unhardened valve seats would last decades in the weekend driver.

I've actually had more problems when using Stabil. I'm not for sure what it's made of, some sort of Petroleum distillate I'm sure. I don't use the stuff anymore.

Ethanol had been used about as long as there has been an internal combustion engine. Henry Ford built the model A-s to run off of it. Even early farm tractors ran off on it. I think the problems come when vehicles/equipment sit for extended periods. Not to mention, the gas that was used throughout the 50s,60s, and 70s was full of Raffienates, Trans-mix, and numerous other things that I would not gasoline. Not to mention that the modern "winter blend" is full of butane. I'm sure it does as much, if not more damage than ethanol.

all I know I just spent the entire day trying to figure out why my lawn mower wouldn't run. I'm pretty sure it was the year old gas...The mustang however runs fine on it. go figure. The truck I drive enough to fill it at least every other week. However you peel it, old gas is bad gas, seems I learned this lesson when I was about 15, should have kept it learned I guess.

If you need gas without Ethanol look at puregas.org, or local air port account avegas can't have Ethanol because it attracts water. Ethanol free gas will usually be a little higher, but less problems.