Need to burn off gas that's been sitting in the tank for about two years (with Stabil added two years ago).
Don't trust the fuel gauge, as it doesn't seem to go below half-way. Is there any harm to the engine or fuel system
if I just let it idle until it runs out of gas? I don't have any way to pump it out and dispose the old gas and don't want to
risk running out of gas driving it around. Thanks in advance!

 

hmm, I have
mixed opinions on that.
cop cars idle a lot.
guess if your idle is tuned well and coolant system is good,
go for it

 

How much gas left in the gas tank?

 

Put a stick into the tank and see how full it is. If it is only a few inches, run it dry. But if it is close to a half a tank I would drain it out. A simple siphon pump available at most auto stores would work. As for disposal a lot of local recycling center have provisions for bad gas/oil.

 

If your car is in decent tune, no issues, let her run it out.

 

Hard to tell how much gas is in the tank, even with the stick method, as I only just started with the stick once the gauge was already showing half full, so I don't have any reference as to where a full tank (or empty) shows
up on the stick. Currently, the gas is about 4-5" high on the stick, so I know I have some fuel left, but just don't know how much and don't want to be stranded out on the road trying to get it down to say, 1/8 or so (about 3 gallons)
before filling it up at there gas station.
Car runs well. Oil and water temps are good letting it idle for 30 minutes. I've read where gas usage at idle is only about 1/2 - 1 gallon per hour. Just trying to get some input as to whether it's ok to let it idle for maybe 4-5 hours.
And also am curious as to whether there would be any damage to the engine and/or fuel pump if I just let it idle until it runs out. Thanks!

 

valve train, over rich mixture, and heat are my only concerns
maybe rev it every 3/4 hours?

 

Good thoughts. I'm putting it away for 6 months. Just wondering, with 2 year old (Stabilized) fuel in the tank, if I end up leaving say, 8 gallons and top it off (about 15 gallons) with fresh (ethanol free) gas and add Stabil,
will I be ok? Just not sure what happens chemically to those old 8 gallons

 

that is more opinion.
some say a full tank has the best outcome
others no
supposedly gas has three month shelf life.
I have run 2 year old gas

 

I would not idle my car that long, safe or not. 4-5 inches, go take it for a 75 mile run, take a flashlight with you and stop and check the level if you are worried...When it's low enough put some 93 octane and more Stabil and be happy...
Or, siphon the gas out and put it in your daily drive, save some for your lawn mower, and etc...
As my dad used to say, don't sweat the easy stuff.....

60

 

very bad for most engines to sit and idle extended periods

top end becomes all crispy coated in carbon sheets,
high temperature and poor oil flow,
poor removal of blow-by gas doesn't help

I wouldn't do it to an engine that I care about , no way

 

My $0.02, if idling for several hours ruins your engine then something was already wrong with it.

Suggestion: Purchase 4 gallon can, fill it with ethanol free gas, strap in passenger footwell. Drive car down country roads until its out of fuel (have fun doing it!). Coast to shoulder. Dump 4 gallons in tank. Drive to nearest pump (with ethanol free gas) and top off tank.

End of the day, you should do what you are most comfortable with.

 

Emergency and public service vehicles users seldom shut them off.
But some are diesel. So, that's a different ballgame.
Emergency vehicles & daily drivers are fuel injected with a pump in the tank, rather than a gummy carb and a well-worn mechanical pump.
Emergency vehicles get oil changes very frequently.

Just my 2 cents. I would not prolong the idle in these old school engines. Bad practice.
Go to Plan B.

 

Thanks for all the suggestions. I'm going to try to drive it until my best guess there's safely about 5 or so gallons left.
I know that the '82s are low compression and only need 87 octane. But is there any advantage in helping
with "boosting" the old remaining gas if I fill up the tank with 93? I of course will be adding Stabil as well.
Just trying to prevent varnish and gumming developing until I take her out again in about 7 months.
(Unfortunately, I'll be out of state during this time with no one available to start her up during this period).

really appreciate the wealth of information on this site!

 

Just saying, race gas is many times better compared to normal pump gas in terms of shelf life. Idk how it is elsewhere but in the southeast there are a lot of stores that sell it. 100/110/leaded/unleaded, many options.

higher octane is not going to hurt your engine. Whether is 93 or 100.
just more expensive for the same or less power.

I don’t think pump 93 last longer than pump 87 though

 

Idling is one thing that is hard on flat tappet cams because of the lack of splash lubrication (this should be well known). I would not do it, no way!!

 

Thanks for the advise.

 

If it were my Car, I would Drain the tank and dispose of the fuelif it has Ethanol in it. Oxygenated gasoline doesn't store very well. You need to put the right ethanol treatment to be able to store it.

Don't feel bad I had to drain my 50 gallon tank in my RV. I diluted it with new gas and ran it through my Buick. Usually it doesn't get 12 months old before an alternate vehicle burns it. Even the left over 2 stroke gas from the end of the fall season.

There is a product called Mechanic in a Bottle and it is advertised to help wake up "old" gas. It worked well for me when I needed to start a car that sat with a full tank of fuel for too long. I drained out ~2-3 gallons and then filled it with Good gasoline and the Mechanic in a Bottle and the car ran like it had new gasoline in it. That gas should have not been able to run as it smelled bad. I ran it through with no ill affects.

 

Just hand pumped/emptied my tank to be able to remove the tank. Hand pump was twenty something at the local parts store, but would prolly have been less on Amazon. I was impatient and wanted it now, so paid the extra few bucks.. Pumped out 3 gallons into an old gas can, and about a gallon into a 5 gallon bucket. Will keep the stuff in the can for miscellaneous washing, etc. The gallon in the 5 gallon bucket I let sit outside for a few days and the gas evaporated away (that was the plan). So, no disposal concerns. No honey bees were harmed during this process. Of this I am sure.

 

You can design an engine to adequately lubricate at idle speeds- of course.
Some engines handle it well enough, such as Nissan sr20 and Toyota JZ series, and perhaps even the Honda stuff.
You can start one of those and notice the cam priority oiling twin squirts pointed at every lobe. Lots of oil splashing around it makes a big mess instantly.

Now, if I start a same year (2002) LS like the LM7 or L33 engine from chevrolet, I can sit there at idle after a cold start for 2 minutes without seeing a drop of oil reach most of the pushrods.
This is typical for those year LS engines. In fact the used L33's often have unnatural pushrod wear on the tips farthest from the oil supply (front of the engine shows abnormal pushrod worn)
After a spirited drive at hot idle, the oil dribbles down each rocker of course, but it doesn't spray strongly like an SBC.

Oil systems are intended to service a wide range of operating conditions. Kind of like an alternator. But just like an alternator, when the rpm is just a little too low, if can fall outside of its intended adequate output, especially when we consider wear and tear, which is another major impact on this discussion. We can't assume, especially when it comes to older engines, that every drop of oil that the oil pump is pumping will reach the top of the engine - there can be worn gaskets, worn or torn o-rings, misaligned parts, worn passages, blocked passages, etc... We don't know. Lubrication may not be adequate at low RPM any more due to these issues which are masked by simply driving the vehicle without much idle time. Remember - keep in mind - an engine can run without oil pressure for a couple minutes. The thin layer of oil protects the engine during compression testing, cold starting, that time between getting oil flow and being turned over but not having oil reach the farthest points yet. We reconcile this with the fact that there is no way to know how much idle time is being covered by 'running without oil' protection due to some issue with oil flow at low rpm. Its anybody's guess.

And we have not touched on the topic of carbon coatings and carbon cycling. The PCV system is responsible for removing hot blow-by gas which is primarily composed of water and inert CO2. In modern engines the control is done via computer and solenoid, directly regulating vacuum as to prevent water from interacting with oil and forming byproducts such as carbonic acid in the presence of CO2. In older engines and less well designed engines, water can be more of a problem in the presence of partially reacted combustion products, i.e. the old engine 'problem' of combustion efficiency (generating partial products of carbon more frequently than modern engines) combined with free, hot water forming from combustion (as part of blow-by) with the advanced monitoring and control over crankcase pressure (another modern invention post 02+ for most engines) makes it much easier for carbon to find a foot hold forming deposits on the engine and able to circulate into engine oil. The heated parts at the top end of a poorly oiled engine near idle speeds, oil is intended to act as a coolant for many pieces, not just lubricant; heated metal with thinning sheets of engine oil being attacked by hot water in the presence of a pressure scalar and excess carbon anionic/cationic structures helps carbon rapidly forming sheets upon sheets of gradually browning/darkening layers of deposits over the crankcase exposed surfaces. Carbon fragments behave this way are able to circulate into oil and around the engine leaving deposits including in oil passages where it partially obstructs or changes the flow kinetics (disruption of flow, de-laminar in capillaries).

To summarize, there are innumerable ways that improper PCV, wear, engineering design, age, oil flow, etc... can make a seemingly harmless idle actually cause rapidly accelerate wear and tear of an engine, Its just not a smart thing to do and there is no up-side