accellerating aging of RUG

Single Tank WVO systems and blending SVO WVO to thin it.

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accellerating aging of RUG

Postby 3lr » Wed Dec 03, 2008 4:08 am

what conditions cause RUG to age (go stale) so when used for blending
there is no clashing between the octane and cetane of diesel and bio fuel oils?
In other words is there a way of accellerating the aging proces and if so,
can one prevent/minimise unappreciable side effects or degredation?

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Re: accellerating aging of RUG

Postby mixelpix » Tue Dec 16, 2008 1:14 am

3lr clashing between the octane and cetane of diesel and bio fuel oils? In other words is there a way of accellerating the aging proces and if so, can one prevent/minimise unappreciable side effects or degredation?


You might consider 2-5% VO (lubricity) and 2-5% PGT (cetane boost), possibly as much as 10% (?) bioD glycerin byproduct (fuel density and burn characteristics) per volume of the stale gasoline you intend to blend with the rest of your diesel constituents. (note: cheapest food grade veg glycerin I have found was 50 pounds for ~$150, otherwise it is really expensive and hard to find in sizes over 6oz.)

That said, I strongly urge you to contact your R.U.G. reseller and ask them for the material safety data sheet on their product. This list of constituents will greatly aid in your quest. Be on the lookout for chemical constituents which will promote the polymerization or oxidization of vegetable oils, like dimer acid, which is a corrosion inhibitor. (di-mer acid, as oppossed to poly-mer, not an acid which is "dim" :D)

Does anyone have any research indicating that when gasoline goes stale and it's octane rating decreases that this affects an actual raise in relative cetane value and how much of an "improvement" in cetane this might be expected to acheive? Personally, I don't think it is the case that when gasoline constituents degrade that this affects an increase in cetane value. Not saying it isn't still a useable fuel, just that so far I have only ever seen anecdotal claims and would love to understand what the process of degradation is from a scientific viewpoint. This would help me alot in applying the SI fuel standards in CI situations, DI or IDI, new, computer controlled and unforgivingly fuel metered or old. Thanks!

3lr wrote:is there a way of accellerating the aging proces

Same as most ways to degrade any and all organic substances:

oxygen, heat and exposure to UV light.

(Yep, fossil fuels are organic)

If you want to quickly "stale-ify" the constituents of R.U.G. blends, consider adding some air stones and "oxidizing" a batch... with a fan in the open air, no where near an open spark. Airstones - cheap at any pet store. (note: I would not do this myself)

Please ask yourself this first: what is the net effect of releasing all those volatile and toxic light fraction fossil fuel distillates and PAH's into the air? Am fairly certain that the UV exposure after their release will decompose them into nasty and ozone depleting compounds.

Personally, I wouldn't do this as a regular course of fueling. I would normally only consider using stale gas in a diesel if I accidentally let a supply of R.U.G. go stale. I usually avoid this by adding a fuel stabilizer to any gas fuels I am not using immediately.

E.g. when I store my 1980 XS1100LG DOHC 1102cc Yamaha "Midnight Special" for the Winter I like to top up the tank with high octane and add a stabilizer. The bike engine runs horribly on anything lower than 91 octane, but starts up fine every time after storage. When I store for more than 4 months, I top up with diesel to avoid oxidization & gasoline varnish issues altogether (also drain the fuel bowls in the excellent 34mm constant velocity Mikuni carbs). I have also been known to top up the crankcase with diesel fuel to prevent the oxidization from long term storage (6mo+) which can happen when old oil sits in a crankcase - often leading to a rim of rust right above the oil as a result of condensation from normal atmo. When I bought a used 1973 90cc Indian, this kind of damage had almost ruined the transmission. A steel brush and lots of love later and she tears up the hills back in here in the woods!

Back to stale r.u.g. in a diesel: bad idea if you are concerned about the Soil Food Web at all. Please note, this is just my humble opinion. Not trying to start a flame war. That said, the detrimental affects as I understand them in terms of performance and efficiency are:

1) lower BTU content
2) anti-knock properties for which the constituents of the gasoline blend are optimally selected for
3) non-polar (vegetable oil) reactivity
4) augmenting constituents for anti-ice, -corrosion, -static, etc...

It is also worthwhile to note that by design (modified, "converted" or otherwise) all of Rudolph Diesels babies will let fuel slip past the rings and into the crankcase oils. Some of the manufacturers have also "optimized" their fuel deliveries and use the crankcase oil to lubricate the fuel pump components. Something to consider when adding gasoline into the loop. As for crank oils, take a look at beef oil based lubes like Green Earth Technologies' G-Oils™.

-Patrick Kennedy
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Postby zag » Mon Jun 01, 2009 7:24 am

Running a gasoline engine on stale gas can cause the valves to stick. Wouldn't it likely have the same effect on a diesel?
77 International Schoolbus DT-466 diesel
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Postby BMW Fan » Mon Jun 01, 2009 11:40 am

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Postby WD8CDH » Fri Jun 19, 2009 10:47 am

I doubt it if stale gas has any higher Cetane rating than fresh. Just because it works worse in a gas engine doesn't necessarily mean it will work better in a diesel.
Ron Schroeder
'85 MB 300DT 2 Tank
Since '81 former WVO conversions:
'83 240D
'80 Audi 4000D
'83 Isuzu Pup
'86 Golf
'76 Honda Civic with Kubota engine
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