Why 80% wmo and 20% gasoline?

Tdglass1

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Matching the viscosity of diesel fuel seems important considering injector flow. So I found an online calculator where you can mix oils and it will give you the final viscosity.

My question is, does this seem right? At around 100 degrees Fahrenheit mixing gas (.6 cSt) and 15w40 engine oil (110 cSt) would produce a final viscosity of around 40 cSt. For comparison #2 diesel fuel is around 3 cSt.

Making the wmo / gas mix 13x more viscous than diesel fuel. Is this ok? Will injectors be able to handle the difference?
 

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Jesus Freak

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I always add this caveat when I discuss WMO: I'm not very scientific. So having said that I will point out, how would you ever know that you only had 15w40? Unless maybe you only used your own oil from oil changes, but you would never have enough to matter. I guess centerfugeing might create a consistency, maybe. But I settle and filter mine mixing gas or diesel until it "feels" right. If you're running an IDI, early Cummins, or anything else that is a mechanically injected diesel, as long as you're close, it'll make the injectors pop.
 

u2slow

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IDI injectors don't spray. They are like a squirt-gun with a single stream.

Viscosity changes some from summer to winter fuel, and when the engine just starts until it's warmed through.

I have yet to blend in gasoline, and my cummins injectors spray with 4, 5, or 6 holes. I have cut fuel as heavy as 50% with wmo in the summer and they still run, albeit a little smokey and 'laggy'.
 

Mt_Man

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I think that 20percent is a common amount of gas blends. To much gas and effects the autoignition characteristics (centaine rating) negatively and cause the engine to run rough. I have heard of people burning up to 30percent gas but not much higher. Be interesting to see other people have learned.
 

Tdglass1

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I always add this caveat when I discuss WMO: I'm not very scientific. So having said that I will point out, how would you ever know that you only had 15w40? Unless maybe you only used your own oil from oil changes, but you would never have enough to matter. I guess centerfugeing might create a consistency, maybe. But I settle and filter mine mixing gas or diesel until it "feels" right. If you're running an IDI, early Cummins, or anything else that is a mechanically injected diesel, as long as you're close, it'll make the injectors pop.
You would never really know. I just took the viscosity of the most common HDMO. PCMO would get you closer to diesel. I guess it would really depend on where you’re getting your oil from. If it’s a place that works on semi trucks, you will have thicker oil, if it’s a Walmart or something you will have a thinner oil.
 

Shadetreemechanic

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You don't need to match viscosity. I have been blending in my IDI for almost 20 years. I tried gas several times, but in my experience was its fine when unloaded, but when you work the motor hard towiing it causes running problems.
I blend 20% with diesel. The result is much higher viscosity than diesel alone, but the only time I have any problems is when the weather is well below freezing and even then its fine once the filter has warmed up from return flow off the IP.
I would not go above 5% gas.
 

TNBrett

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I’m no expert here, but the formula that that calculator uses may not be very accurate for what you’re trying to figure out. If the formula is just averaging the viscosities based on the ratio, it’s ignoring the solvent effects of the gasoline. It would be pretty easy to perform some tests to determine the viscosity on your own. The actual numbers don’t matter, if all you’re wanting to do is get relatively close to the viscosity of diesel. I’ll add a video to show you the “right” way, but you could easily perform the same test by poking a hole in a soup can with a nail, and timing it with a stop watch. Use the time it takes for diesel fuel as your target, and alter your mix to get closer.
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Jesus Freak

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I think that 20percent is a common amount of gas blends. To much gas and effects the autoignition characteristics (centaine rating) negatively and cause the engine to run rough. I have heard of people burning up to 30percent gas but not much higher. Be interesting to see other people have learned.
When I first got into the wmo thing, the first 300gals I got came from an old school (he specializes in 70s 80s 90s stuff) junk yard. And there was a bunch of rotten gas in it, you could smell it, but that stuff made my truck run so smooth it was amazing! I've been running stuff, I've got @200gals left, from a big equipment company. I think it's got a bunch of hydrolic oil in it. I don't like it, I think it's gumming up my filter every couple of weeks but a fuel filter is cheaper than a gallon of diesel! Im thinning it with about 10 or 15% gas, and if it doesn't seem right I'll put a couple gallons of diesel in the tank on top of it.
 

Tdglass1

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I’m no expert here, but the formula that that calculator uses may not be very accurate for what you’re trying to figure out. If the formula is just averaging the viscosities based on the ratio, it’s ignoring the solvent effects of the gasoline. It would be pretty easy to perform some tests to determine the viscosity on your own. The actual numbers don’t matter, if all you’re wanting to do is get relatively close to the viscosity of diesel. I’ll add a video to show you the “right” way, but you could easily perform the same test by poking a hole in a soup can with a nail, and timing it with a stop watch. Use the time it takes for diesel fuel as your target, and alter your mix to get closer.
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That video was great, pretty easy to test. I wonder if anyone has tried it before on here?
 

Tdglass1

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You don't need to match viscosity. I have been blending in my IDI for almost 20 years. I tried gas several times, but in my experience was its fine when unloaded, but when you work the motor hard towiing it causes running problems.
I blend 20% with diesel. The result is much higher viscosity than diesel alone, but the only time I have any problems is when the weather is well below freezing and even then its fine once the filter has warmed up from return flow off the IP.
I would not go above 5% gas.
Good point, temperature plays a big factor in how thick the oil is. I wonder what the temperature is as the mix is reaching the injectors?
 

Tdglass1

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I think that 20percent is a common amount of gas blends. To much gas and effects the autoignition characteristics (centaine rating) negatively and cause the engine to run rough. I have heard of people burning up to 30percent gas but not much higher. Be interesting to see other people have learned.
True, I didn’t realize the auto ignition temp for gas was higher than diesel by over 100 degrees. By the time it reaches the cylinder I bet it’s well over that temp though.
 

Mt_Man

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I have a summer and winter blend I run here in oregon.

I have noticed that there engine runs better with warm fuel vs cold. Cold start(still starts easy)/first part of the drive vs after a long trip/hours of engine run. It would be interesting to have several temperature probes to see home much heat it absorbs throught the ip, line, and injectors from the engine. Been meaning to add a inline fuel heater (post filter), temp probes pre and post, and make it adjustable.

(Gas) Has higher auto ignition temp but lower boiling point. So could boil it out really easy with heating during cleaning and prossessing. SDS sheets have all the auto ignition temperatures, boiling points, etc. Kinda interest info. I have been wondering if while gas has a higher autoignition temp if it helps wmo burn better. With my m35a2 and wmo. People talk about blending gas and could cause damage (over heating the heads and over speed the turbo). But the ltd-465s have 22:1 compression ratio to burn pure gas with motor oil to lube the injection system. With that I notice what my turbo sounds like and blend my fuel to make sure that turbo sounds healthy and not to low. I had some mixes that didn't spool up the turbo enough and I stepped up my gas ratio till I found a ratio I liked and got good performance with stock fuel system. My other though is how easy the truck starts cold with out block heater. Thin to where it starts easy.
 

Mt_Man

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That video was great, pretty easy to test. I wonder if anyone has tried it before on here?
I have a craftsman visco cup and test some blends against it some diesel I have. I just check it to see how close it is. But I haven't used it with the wiz-wheel calculator. But that is a resent use.
 
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Jesus Freak

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I gave up on my glow plug system and just start my truck on ether. With a brief shot it fires right up and then I let it idle until it's warm. I know there'll be mixed reviews about that but it works. Below 50° it takes a little more spinning and a couple shots of ether. I really need to raise my bar and get more scientific with my WMO, though I kinda think there might not be an exacting science to it. It might just be an on going experiment, I mean..... pumping out a 500gal waste oil tank is like a box of chocolates, you never know what you're gonna get....
 
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