Mix of Fuels to Save $ - page 1 - General - VWDiesel.net The IDI, TDI, and mTDI source.

• Mix of Fuels to Save $ by ORCoaster on 01 Jul, 2012 23:20
• Well after I spent all kinds of money to install a second fuel system to run WVO in my 81 Rabbit I ran across an article that claimed you really don't need to do anything other than to blend filtered oil with regular diesel.  WHAT?  I can buy the no gel effect but only in warm climates.  I can't see how the blend can keep from coking at low temps either.  I have a FPHE on my system and until I ran the return loop back to the front side of the heater I was only able to get 147 degrees to the inlet of the IP.  That is still to low in my opinion for WVO. 
  
  So has anyone heard of this "new method" in the past.  I know we had the waste oil or used oil mixed with RUG here on the forum but this is the first I have picked up on a Veg oil/ diesel combo.  Any thoughts on the value of doing this mix?  Drawbacks? 
  
  Maybe I won't sweat the little bit of WVO that might kick back into the diesel if I don't switch off and purge the pump like I should.
  
  
• #1 by RustyCaddy on 02 Jul, 2012 02:56
• was mixing up to 20% WVO to 80% biodiesel a few years back as a summer fuel mix (in hot southwestern Oregon).  stopped when polymerized WVO started showing up as a thick molasses in the bottom of the pan when the oil was drained.  That motor had a lot of miles and needed a rebuild though and have never pulled the pistons to see the coking/no coking that might have resulted.  If you have good compression...that would be reassuring?
  
  people mix up to 50/50 (VWcaddy.com).  Diesel and WVO also can chemically react to form a filter plugging sludge (especially if the is WMO in the mix).
  
  Justin at Greaseworks in Corvallis recommends adding 10-20% biodiesel to the veg oil in a two tank system as one way to deal with lower WVO system temps...the blend lowers the viscosity in heated oil.
  
  The maker of Greasecar systems use to post that since the injector is a very hot heat exchanger that WVO is probably near 180 degrees when injected even without much pre-injection pump heat...i have gotten temps in the 168 to 176 range using a laser heat gun at the base of the injectors.  Think that Turbogreasel here on the forum has some experience about injection pump compression heating of oil.
  
  i don't worry about getting WVO in the main tank, just switch to the main tank every so often and run the truck up and down the highway for a week to burn up the biodiesel with the WVO before to much WVO builds up...it also seems to "reset" the system for going back to WVO for highway driving again.
   
• #2 by 745 turbogreasel on 02 Jul, 2012 04:34
• Quote from: ORCoaster on 01 Jul, 2012 23:20

  Well after I spent all kinds of money to install a second fuel system to run WVO in my 81 Rabbit I ran across an article that claimed you really don't need to do anything other than to blend filtered oil with regular diesel.  WHAT
  

  It will work fine till you have to start cold but can't, or you are stuck on the side of the road trying to figure out how to clean the inside of your tank, wishing you at least had a redundant line and separate filter.
  1% usually wont cause any problem for a long time.  99% will probably give you some issue fairly soon.
  
  I just switched and dove a 2 miles on diesel, never really purged, and my 200,000+mi injection pump pulled 3 years before having problems, but it also switched to ULSD during that time span.
• #3 by mtrans on 02 Jul, 2012 13:32
• Yes,right Q is how much,and glory one how long?
• #4 by ORCoaster on 02 Jul, 2012 15:28
• I figured this mixing had application in a very narrow range of situations and since I am in the cold long enough I chose to install a heated tank and a couple of exchangers to boot.  I was just taken aback by the idea.  To easy I said. 
  
  I know the BioDiesel troubles folks have with putting that in where they used to put diesel and getting all that crud into the filters and such or degrade lines and end up putting on something that can take that type of fuel as well as diesel. 
  
  I think I have the purge figured out to be two minutes from where I park at both ends of the long highway trips.  Speed is kind of slow so engine is running low RPMs but not idle either. 
  
  I don't want the sludge problem that comes from mixing fuels either.  Some people don't like their food to touch on the plate when they eat it and I don't like my fuels to touch either.  Just one more maintenance headache as far as I can tell.
  
  Rather than mix BioDiesel in with the WVO I re routed my return loop to the front side of the FPHE to get hot again and that seems to be the way to do it.  On purge that little bit of fuel pushing back into the filters isn't going to be a bad thing as far as I can see. 
  
  I don't buy the injectors heating the oil all that much.  Like you say the temp just isn't there like it should be.  I don't plan to insulate them either. Diesel may not work as well with that kind of heat. 
  
  Thanks for the feedback seems like there are problems with mixing it, which is why I went two tank system.  That way I can always get home even if it costs a bit more.  It has to be dependable to drive on it. 
  
  
• #5 by R.O.R-2.0 on 03 Jul, 2012 01:16
• there is NO WAY IN HELL i would EVER fire a COLD diesel on ANY PERCENTAGE of vegi oil..
  
  do you value your compression?
  
  is the money you save on fuel going to make up for the rebuild required because of the coked up rings?
• #6 by mtrans on 03 Jul, 2012 04:52
• Quote from: ORCoaster on 02 Jul, 2012 15:28

  On purge that little bit of fuel pushing back into the filters isn't going to be a bad thing as far as I can see. 
  

  
  Do you have valve before filters?,I put mine AFTER.I never understood why before.
• #7 by ORCoaster on 03 Jul, 2012 10:27
• All valves after the filters.  But on purge the diesel comes in and the veg oil still reroutes to the return loop only it can't get back in as the first valve is closed so pressure has to go back into the filters.  Only for a few minutes. Then I switch to let return to tank flow thru second valve.  All electric 12 VDC
• #8 by fatmobile on 03 Jul, 2012 15:28
•  The flushing have to go somewhere, best they go backwards down the vegy line;
   Backflushes the filter,.. the stuff settles to the bottom of the filter while sitting and stores a thinner fuel in the filter.
  
   You don't even need to heat the car up before switching.
   Switch to vegy and start the car.
  
   It starts on the diesel in the injectors and pump,.. then the thinner stuff you flush comes into the loop.
   Probably running on a blend of 90% diesel while it warms up.
  
   Vacuum gauge on the fuel line is manditory.
   Even if you aren't running on vegy; to see how hard the pump is pulling.
• #9 by ORCoaster on 03 Jul, 2012 22:45
• Hey, idea time!  I have a place on the top of the final filter that I am using that I could insert a fitting and hook up a pressure/vacuum gauge.  Then I would know both numbers as needed.  Vac under normal haul and pressure at purge.  Now what did I do with that combo gauge? 
• #10 by fatmobile on 04 Jul, 2012 13:20
• Vacuum gauge is plenty, unless you have a helper pump on one of the systems.
   
   Best to connect the vacuum gauge to the front of the pump, so it'll work when you are on diesel too.
   Even my cars that aren't converted to vegy have one, diesel tanks/systems clog too and vegy usually makes it more likely to have problems with the diesel fuel system.
  
   It shouldn't be any harder to push fuel backwards through the filter than it was to pull it forward.
• #11 by ORCoaster on 04 Jul, 2012 21:51
• I don't know about that ease of flow under pressure versus vacuum.  I think you can pull better flow with a vacuum than push with a pressure. 
• #12 by mtrans on 05 Jul, 2012 03:45
• Parhaps is that is because there is fuel filter made for vacuum and presure ones,so I think that vacumm FF will make air in more eazy,and I put mine for presure.
  ps.I dont know now what is original setup in my Fiat anymore.
• #13 by the caveman on 05 Jul, 2012 07:56
• You will always get some blending from one tank to another, the only thing to do for winter is to keep the diesel tank topped up. The other issue you are having with VO not warm enough is to install a Plantdrive vegertherm 12v heater. I have now run 3 vehicles on WVO heated tank, filter Vegetherm no heat exchanger for a combined milage of more than 300,000kms. 3 engines have very good compression, 2 pumps that were opened and checked had zero wear. I drive in heavy traffic so the coolant temps drop off, but with a Vegetherm it's not really an issue. Oh and none of them are looped.
• #14 by ORCoaster on 05 Jul, 2012 22:27
• So I had a short bit of running around to do so I fired it up cold on diesel.  Temp on the inlet side of the pump was 70.9.  I have a 12 vdc digital temperature probe on it so I know what it is 2 inches from the IN banjo.  I pulled away from the curb and watched for the water temp gauge to give a bump.  1 mile down the road I flipped it over to veg oil.  Went another 1/2 mile and shut it off, temp was 109 on the fuel line.  Quick in and out of the store and it fired right up on veg oil.  Don't think it had much in the IP at that point.  Drove another few miles, about 3 and was looking at 120 on the fuel temps. Slow traffic of 30-35 MPH.  About another 2 miles and I was nearly back to the house and was looking at 140, over to purge, two minutes later pulling back to the curb so to middle position on the rocker switch and I was set to refire on diesel.  Temps at 109 and dropping. 
  
  Had the neighbor tell me the logging outfit he works for may have large quantities of used hydraulic oil available.  Anyone burning that for fuel?  Wonder how well it does.