Home Our System FAQs Installations Contact Us
Our Customers Forum Products Info/Links News/Events

Our System

System Description
System Operation

The following is a description of the V.O. Tech system and how it operates. It is designed to absorb as much heat as the engine generates and use it where it is needed most.

System Description

The V.O. Tech system is uniquely designed to absorb as much coolant heat (or waste heat) as possible and to use this heat to warm the vegetable oil. According to the most reliable studies available, in order for vegetable oil to be used safely as a fuel in a diesel engine, it needs to have the same viscosity (typically measured in centistokes) as traditional diesel fuel–see report .

When the vegetable oil reaches a sufficiently high temperature it will also develop the same lubricating properties as diesel fuel. Viscosity and lubrication will prevent carbon buildup and coking on the inside of the engine, which will prevent premature engine failure

As the engine warms up on diesel, so does the vegetable oil. This is accomplished by heating the core of the system known as the “GEO” (patent pending).


The design for this multi-function heated filter housing took years to develop but even the first prototypes produced impressive results. The basic concept incorporates a coolant heated filter housing that uses a bath of coolant around an adequate supply of vegetable oil.   Determining the correct size of the supply balanced two important criteria; making it large enough not to starve the engine of fuel during load demanding situations while at the same time, not making it so large that it would waste energy and heat. In the end, this balance resulted in a highly efficient design.  Another consideration was to allow for an even heat to prevent temperature spikes within the fuel system.

Incorporating all system components to function in a single unit (multi-function filter housing) was also a main consideration in the design. Our goal was to include all of the necessary components in a single unit. Most existing kits use multiple separately mounted components in an attempt to achieve the proper level of heat. This results in numerous gadgets mounted in an already tight engine compartment. With all this extra apparatus under the hood, several things are going on: The fuel line ends up significantly longer and countless additional plumbing fixtures are needed. The resulting contraption can become nothing more than a large heat sink, and, in some cases, can actually loose the very heat you are trying to retain.

Instead of mounting separate components in numerous locations, the V.O. Tech system is an all-in-one design with an easily replaceabale filter in a coolant-heated oil bath with a minimum of ten (10) micron filtration. The filter has more surface area than some of the largest filters now used in this market.  All solenoids are connected to a fuel control manifold (patent pending) which is attached to the filter housing with no fuel lines in between (except in extremely tight engine compartment applications where limited space requires the components to be separated). The multi-function fuel manifold distributes the fuel according to valve operation.  It also includes:

  1. A sight glass window on the return fuel side to allow for 1) monitoring fuel flow and 2) air in fuel diagnostics in both diesel and vegetable oil modes. 
  2. A vacuum/pressure access port on the feed side to allow for monitoring restrictions in the vegetable oil filter and in the diesel filter, depending on which mode the system is being operating in.

At the bottom of the filter housing is a regulated 10 Amp disc heater that will automatically shut down once it reaches 175 degrees (after the coolant heat has brought the oil up to a safe temperature to inject). The filter housing has a simple removable screw cap which allows easy top loader filter service.  It also has a combination water drain/water sensor on the bottom which sends a signal to an LED panel letting you know if free water is indicated in the housing.  This drain is very helpful during filter service and the sensor is highly sensitive to the detect the slightest levels of water or anti-freeze in fuel (in the unlikely event that cross contamination occurs).

An oil temperature sensor is also mounted in the housing. This sensor reads the actual oil temperature inside the filter housing to let you know precisely what the oil temperature is before you switch over. It is extremely important to understand that during warm-up, coolant temperature does not necessarily equal oil temperature; in fact, it usually does not. With the sensor mounted in the filter housing questions regarding these previously unknown temperatures are easily answered.

Another feature incorporated into the design of the filter housing is the ability to flush it out without back flushing the filter (back flushing the filter is undesirable because it sends filth back to the fuel tank). Soaking the filter in diesel after flush extends filter life because the diesel fuel helps dissolve any polymerization or wax crystals that may have formed on the element.

For example, in a situation where the driver forgets to flush, an alert tone will sound at engine shut down to provide a warning indicating that the oil has not been flushed out of the system.  At that point, the driver should re-start the engine and flush.

The Evolution of the Geo…

System Operation

The system uses a simple 3-position switch.

  1. The engine is started with the switch in the “Diesel” position.  At this time, the vehicle is using traditional petroleum-based diesel to start and warm up the engine. During this warm-up period the operator can monitor vegetable oil temperature at the filter housing before switching over.
  2. Once the engine and vegetable oil reach sufficient temperature the switch is placed in the “Veg. Oil” position (switchover to veg. mode).  After switchover, the vehicle is fueled by straight vegetable oil.
  3. At shutdown the three-way toggle switch is placed in “Purge” mode. Veg. oil is washed out of the system (preventing it from solidifying in the fuel system).  Purging also prevents engine-damaging coking and internal engine carbon buildup.  The amount of time required for a complete system wash depends on the particular application and varies widely from one vehicle to another.  It is a function of fuel system type and flow rate and could range from as short as four seconds to as long as two minutes.


During the initial warm-up period (diesel), the driver can monitor for diesel filter restriction using the vacuum boost gauge.  After switching over to vegetable oil, the system allows the operator to monitor for vegetable fuel filter restriction.  Monitoring for filter restrictions allows the user to service and replace either filter (diesel or veg.) before performance issues may arise on either fuel.  Eliminating the potential for a dirty filter helps reduce the incidence of costly breakdowns (which could otherwise result from failed components such as lift pumps and injector pumps over-stressing the fuel system).

Return to Top

System Components and V.O. Tech Firsts

  • Gates ¾” Green Stripe® II hose (thick wall) heater hose is used because of its excellent insulating qualities.  "Gates Green Stripe coolant hose exceeds the requirements of SAE J20. Not only does it resist electrochemical degradation, its burst strength far surpasses the SAE specification when tested with eight brands of ethylene and propylene glycol, and OAT-based coolant concentrates." (www.Gates.com/Automotive).
  • High temperature rated heater hose insulation prevents hot exhaust from melting into the hose and keeps heat where it is needed.
  • Fuel line insulation for IP and veg. oil lines.
  • All Viton or synthetic seals and 3/8” fuel line is all bio-diesel safe
  • Flush alert.
  • Custom in-tank heat exchanger with five foot long coiled aluminum twist tube concentrated in a six inch diameter cylinder keeps the heat in the pickup area while preventing wasted energy heating the whole tank where it is not needed.  This reduces polymerization and saves energy.
  • Custom fuel bowl design for fuel pickup reduces air entering system on hard cornering and acceleration.
  • All components are aluminum, stainless steel or brass (since copper reacts with vegetable oil, it is not used in this system).
  • Custom made in Sweden, our reusable lined hose clamps reduce air leaks and do not eat into or cause damage to the hose.
  • Aluminum fuel line for hose-in-hose-in-insulation (HIHI).
  • Custom engineered and made in our CNC shop, this top loading heated fuel filter housing (patent pending) uses both coolant heat (which surrounds the filter) and an electric base plate heater (to start the heating process the instant the engine is turned on).  The Geo includes an easily replaceable and readily available filter, water drain/ water-in-fuel indicator and air bleeder valve.
  • All 5052 grade aluminum custom fuel cells for a variety of applications.  Fuel tanks use long lasting stainless steel fuel senders which help reduce vegetable oil buildup.
  • Complete gauge package (fuel level, oil temperature and filter vacuum gauges) included.  The oil temperature gauge allows the operator to monitor oil temperature before and after switching over. The dual functioning vacuum boost gauge allows monitoring vacuum/boost for both the vegetable oil filter and the stock diesel filter.

The V.O. Tech system was never intended to be cheapest on the market – only to be the best available.  We encourage you to conduct your own research to see for yourself.