Old diesel fuel. How old is old?

[Kernopelli]

I finally got my engine rebuilt and back in my tractor. I posted about this back in Dec '11 http://www.tractorbynet.com/forums/parts-repairs/229853-seized-engine-need-some-advice.html ( I worked 1700 hrs of OT in 2012 and '13 is no different so far + rental business, family, church etc....so the tractor project went slowly). I had a full tank when we spun the rod bearing and have heard many times about using fuel that is much older than 18 months.

I checked it for algae ( none) and decided it would be fine. When I test started the engine it seemed fine but after actually running it in the tractor it was immediately apparent it ran like crap. I would estimate 75% power and sputtered/ seemed to miss. At first I thought the rebuild was bad but quickly considered it could be the fuel so I drained the it and cleaned the sediment bowl and she runs awesome!

While trying to decide if it was a fuel or engine problem, I read "The University of Idaho conducted tests on the life expectancy of fuels to determine the time line of degradation of stored #2 diesel fuel. The results indicated 26% degradation after 28 days". Seems almost unbelievable based on personal experience and everything I've read about other's experiences with being "gifted", given, etc. old, stored fuel.

So, what are other's opinions on this? I know for fact I have had fuel much older than a month and can't tell a difference between it an pump fresh. I also know now that 18 months and it is good for burning brush, not small diesel engines.....where is the real point that it loses noticable volatility?

 

[TripleR]

I think the oldest I have used was about two years and it ran fine, I am sure others have used older.

 

[Dan Hunter]

I stored my 94 6.5 TD for three years with a full tank. When I took it out of storage it got lousy fuel mileage but ran fine. The next tank saw normal mileage. I wouldn't give it much thought or concern.

 

[newbury]

I've an '88 E350 7.3 that was last FILLED about 6 years ago. For the last four years it's been driven about 20 miles per year (I know, I'm bad). I added about 4 gallons last year. I ran it yesterday.

 

[Blaneypark]

Just looked at a JD that had sat for 8 years in storage. The owner put a new battery in and after about 30 seconds of cranking it started right up.

 

[Kernopelli]

Thanks. These are the same stories I have heard a thousand times. I will admit I didn't have any problem starting but under any load it would not produce good power, was slow to rev and sputtered/missed. I have to assume I got some already degraded/bad fuel to start. I had never heard of diesel being "bad" after 1-2 yrs. and you could have certainly used it, but on a compact machine ( 24 hp) it was REALLY noticeable.

 

[Blaneypark]

Add some "Power Service" to your fuel. It will clean all the inside of your fuel system.

 

[MtnViewRanch]

We have twice bought old stuff with 40+ gallons of fuel well over 10 years old and it has run fine. It might be a problem if exposed to light. The equipment that we bought had-has metal tanks and there was no light infiltration at all.

 

[RickB]

Drain the tractor's tank and see if it runs well on a known quality fuel. When you get it straightened out, put the old fuel back in it. You likely have some problem other than fuel quality.