I still have gas in a container in the shed that was meant for a mower. It is just regular 87 octane. This was from last fall. I don’t want to put it in my mower in the spring, but could I put it in my vehicle when I fill up since the old gas will be diluted with about 16 other gallons of new gas?
Yup, you should have no problem doing this as long as your owners’ manual recommends 87 octane. Actually, even of your car requires premium you should be fine with a 16:1 dilution ratio.
Pour it into your car, I do this every year and never had any problems. I even had about a half gallon mixed with a 40 to one fuel mix…when I added this made sure I had almost a full tank. Won’t do any harm, as most gas additives you buy in a can contain some petroleum oils.
That’s what I’d do. But I always use Briggs fuel stabilizer year around for my small engines with the non-oxygenated gas. Haven’t had any problems since.
As long as the cap was on the fuel can and no water got in it, it should be ok to mix with a full tank in your car.
If stored over the winter during cold weather and the cap was tight, “probably” no problem. But, before I put it into a $30k vehicle, I would dilute it and use it in my lawn mower or take it to a waste disposal area. I hear nothing wrong with everyone’s good advice. It’s just advice for you and your car. Realistically, I personally don’t put OLD gas that hasn’t been treated and has been stored outside in a shed in any of my cars…but I would yours. ;( Don’t mean to be a wise guy but take all of our advice with a grain of salt. There are things we say, and things we do; and sometimes they don’t match. In your particular situation, why be a cheapskate ! Be more cautious next time and dump it in in the fall. To be clear…not me .
Our landfill has a tank for used oil and as well for stale gasoline and diesel. It’s right inside the gate.
You must have access to a similar facility. Why try to save a few bucks and potentially screw up the fuel system of an expensive car?
To each his own. I wouldn’t hesitate to throw a gallon or so of 6-month old gas in my tank, well diluted of course with a full tank of fresh gas. I’ve done it several times and never had a problem.
I’d bring it to the landfill. We have a tank like Doc does, and a boiler that burns the old stuff in the winter for heat at the dump. The “dump” in our case also has some offices and is where the town trucks and equipment are kept.
But I cannot offer a reason for doing this other than being a basically insecure person. A gallon of old six month old gas diluted into 15 gallons of fresh gas should pose absolutely no problems.
@same
6 month ? Are we sure ?
Let’s examine the situation as a basis for both our “insecurity” . If the gas in a tank was left last fall, it does not mean it was bought last fall. No indication of treatment and could have sat for months longer pror to the fall during a really warm, humid summer in a hot shed. How much really old gas was in tank before that was maybe half filled ? Too many variables to be used in our cars and I am just as paranoid. 
and diluting does not make bad gas good. It just mitigates some of the effects…we are both insecure for good reason.
Just for interest, here’s a post from the “bobistheoilguy” website from a guy who has apparently reused a lot of old gas:
"I have encountered a similar situation at work, I have aproximatly 200 gasoline powered boats (not including the 400 deisel powered boats) that I store and maintain. One of the things I havet to do is de-fuel the tanks and fuel bowls and preserve the engines for long term storage.
… We double filter the used gas and add it to our forklifts and small equipment like gensets, air compressors and chain saws. We have even used it in our work vechicles with no problems. We try to use a 3:1 or 4:1 mix of fresh gas with old and add a fuel stabilizer (it’s mostly ethanol). Every now and then something might run a little rough and in that case we drain it out and add a little more fresh gas.
So long story short, filter it, drain any water off the bottom and use it in your lawn mower just cut it down with some fresh gas first and add a little fuel stabilizer. DO NOT pour it on the ground!"
I routinely leave gas in the tanks of my lawn mower and snowblower during the off-season. Never a problem the next year; they fine right up and run fine.