NPG+ contains a non-toxic blend of glycols rather than just propylene glycol. It exhibits improved heat transfer and viscosity characteristics as compared with NPG, while retaining all of the non-aqueous operational advantages of NPG. Both products are inhibited against corrosion. NPG+ is our recommended coolant.

No. Only Evans NPG and NPG+ are considered lifetime coolants. NPGR is currently a 5-year coolant when used for street or a 1-year coolant when used for racing. NPGR coolant life depends on the amount of racing. NPGR has the lifetime additive package but has not been available long enough to receive a lifetime rating. A lifetime rating will be given to NPGR once enough history is collected.

In the past we have suggested propylene glycol or ethylene glycol based regular anti-freeze in small quantities as an emergency substitute for Evans Waterless Coolants. Research has shown that the potential of contaminating your Evans Waterless Coolant increases when adding uninhibited coolants due to what is called "black coolant." Black coolant is an industry wide problem when the coolants are contaminated, because of the multiple variations on the market today of regular coolants. Evans suggests adding nothing except an Evans Waterless Coolant or Evans Prep Fluid to your Evans Waterless engine cooling system.

Evans NPG, NPG+, and NPGR freezing temperature is determined by the viscosity change to where the coolant will not flow through the system at the state temperature. This state of super cooling causes the coolants to contract rather than expand like water-based anti-freeze making storage below the rated freezing point possible. Evans Waterless Coolants do not freeze like water, rather they gels at their freeze points, beyond that it crystallizes. Because Evans Waterless Coolants contract when it gels instead of expanding like water when it freezes, our coolants will not cause engine damage in severe cold weather.

The coldest suggested operating range for each coolant is:
NPG: -79° F freeze protection, +32° F coldest suggested operating temperature. NPG is the thickest of Evans Waterless Coolants and requires modifications for use in lower temperature ranges.
NPG+: -40° F freeze protection, -20° F to -30° F coldest suggested operating temperature with proper warm up or block heater. NPG+ is a year-round coolant and the only coolant for diesel engines.
NPGR: -10° F freeze protection, +32° F coldest suggested operating temperature. NPGR was originally developed for racing only and is NOT suggested for cold weather operation. NPGR can also be used on the street in copper brass radiators due to the lowest viscosity.

Color change is another misunderstood characteristic of Evans Waterless Coolants. All Evans Waterless Coolants will change color. The identifying dyes are designed to be mixed with water. Because of the lack of water in an Evans Waterless cooling system and the heat cycles, the coolants go through an aging process that darkens the coolants over time. The change in color is also attributed to the amount of dirt particles in the system when converted to Evans Waterless Coolants. The higher viscosity of NPG, NPG+ and NPGR at room temperature keeps dirt particles suspended thus adding to the darkening appearance. The color change in no way effects the coolants abilities to transfer heat. The number of heat cycles and their severity determines how fast the color change occurs. At some point all the Evans Waterless Coolants will look dark brown.

YES. Evans waterless coolants are compatible with all metals, because there is no water in our coolants and - no water should be used with Evans coolants - there is no electrolysis. We also eliminate corrosion - as long as the coolant is installed properly and all residual water is removed prior to filling with either NPG+ or NPGR.

NPG+ or NPGR are the only 2 recommended waterless coolant for these applications. NPG+ can be used year round and is suggested for bikes and ATV either used or stored in cold weather areas. NPGR offers excellent heat protection in high temperature use - and is designed for seasonally use only.

NO. You may use your standard radiator pressure cap. In fact, we recommend a 7lb cap to keep NPG+ from absorbing water from the atmosphere. Some users found they could smell coolant, again a 7lb cap eliminated the issue. NPG+ will still cool your system with industry leading efficiency. Of course if you'd like to run a low pressure or even zero pressure system, you will need to purchase a low pressure cap or modify your existing cap. Please consult our tech pages or instruction guide (or call us) before modifying your existing cap!

In most cases changes to cooling system components (pumps, radiators, pressure caps, etc.) are not necessary to use NPG+.

NPG+ is preferred to NPG in all cases except where the ingredient ethylene glycol is specifically prohibited (e.g., use at certain race tracks).

In most cases you would not. However, for applications requiring the optimization of the cooling system for increasing spark advance or increasing compression ratios in race cars, for example, the Evans ancillary products are appropriate. The Evans pumps, radiators, and other components improve cooling by increasing the coolant flow velocity through the engine and radiator.

Standard coolant is comprised of ethylene glycol and water in equal parts, each represents half of total volume. Our Non-Aqueous Propylene Glycol, NPG, as the name suggests, contains NO water.

We have a growing dealer base where NPG+ can be purchased. You may also buy direct from EVANS using our online order form or by calling us toll free at 888-990-2665. Have a favorite speed shop or auto parts store? Ask them to carry EVANS products!

If your system already has the effective flow rates needed to run with NPG, the answer is YES. Unfortunately, most vehicles, with the possible exception of large heavy duty engines and motorcycles, need some sort of modifications to establish the necessary flow rates required for effective operation with NPG. However, in most cases NPG+ (not to be confused with our older NPG) is a drain and fill product.

While these numbers may vary slightly; Small Block engines typically require a minimum of 4 gallons while Big Block engines require at least 6 gallons.

In general, many stock cooling systems can be quickly rendered NPG ready by the introduction of a lower pressure radiator cap and a higher flow thermostat. Additional Evans components may be required as determined by the size and horsepower of the engine, the local ambient temperature, current radiator design (tube sizing and the diameters of the inlet & outlet), coolant pump efficiency, and even driving style. Evans Cooling Systems has cooling hardware packages specifically designed for the adaptation of NPG on medium and large block Chevies.

For systems up to 300 HP without A/C a radiator configuration with 4 rows 1/2" tube copper / brass. Systems 300 to 400 HP with A/C a radiator configuration with 2 rows 1" tube aluminum. System operating over 400 HP need a minimum of 2 rows 1.25" tube aluminum.

The normal operating range of standard coolant (ethylene glycol and water) is 160°F to 230°F with some cooling systems able to function reasonably well up to 240°F; although as this extreme temperature level is reached, the engine will almost always operate with ever less power and response until it boils over and stalls. At approximately 330°F the coolant warning light would normally light up; a cooling system operating with the more modern needle gauge would indicate higher coolant temperatures as they developed. As NPG contains no water, coolant temperatures can rise to higher levels without a negative impact on the performance of the engine. In fact, with NPG in many cases the activation of the coolant warning light represents a false warning as NPG works very well at 330°F. Gauges may show the needle at 330°F, a temperature probably located in the red, but again, no concern is warranted with NPG coolant.

With some explanation the answer is YES! Operationally detonation (pre-ignition) saps horsepower. Detonation is caused by the presence of excessive water vapor in the engine cooling jackets alongside the cylinders. And again, as NPG has no water, there is no vapor and detonation is eliminated allowing the engine to recapture improved fuel economy, emissions, and horsepower. Also, this NPG cooling flexibility allows the engine to effectively control the added heat generated by the additional power realized through the development of higher cylinder compression and/or more aggressive spark timing. Remember, more power means more heat radiated into the engine's metals and fluids. Historically, racing cars have utilized NPG coolant to effectively thermally manage their engine running with up to a 16.5 to 1 compression ratio.

The power (parasitic loss) needed to operate a coolant pump running with NPG is increased over that which is needed to drive pumps working with standard coolant. However, this parasitic loss is minimal when compared to the horsepower gains (see above). And, pumps utilizing more efficient impellers and housing designs can decrease this power loss significantly, often times bringing parity with operation on standard coolants.

No. Because of the low horsepower of most vintage cars, NPG can be used in most applications without modification to the existing engine and does not require changing the radiator.

What are the CHEMICAL AND PHYSICAL PROPERTIES of NPG, especially as compared to water and standard coolant.

In CARS & TRUCKS the elimination of water from the coolant prevents the occurrence of detonation which, in turn, improves the efficiency of the air/fuel burn. This increased burn efficiency can be measured in improvements in emissions, fuel economy, and, as mentioned above, power. In TRUCKS additional fuel economy can be realized by adjusting engine fan control to activate at higher temperatures; thereby decreasing the amount of parasitic loss (fuel/horsepower needed to drive this engine fan). Note that additional fuel savings can be developed by operating with more advanced spark timing (MBT).

In order to increase COOLANT FLOW, the Evans manual suggests eliminating the thermostat and plugging the flow of coolant through the bypass. Will the resultant increase in coolant flow decrease the effectiveness of the RADIATOR?

NO. Slower coolant flow through the radiator increases the incidence of temperature drop (T), however, this same slower rate also allows for more heat to be added as coolant flows through the heads. Conversely, higher coolant flow rates through the radiator generate less heat loss with less heat being absorbed with flow in the heads. Important: If the thermostat is removed, the bypass must be plugged, or it will scavenge coolant (flow) away from the radiator which will result in the cooling system running warmer than normal.

Operating in conjunction with the bypass circuit, the thermostat, when closed, prevents the coolant from running through the radiator by directing flow through the bypass and heater circuits. The sole intent here is to increase the speed of engine "warm up." As the thermostat opens, ever more coolant is allowed to flow through the radiator, an event which allows the radiator to initiate control of and ultimately thermally balance the cooling system.

The specific location of the bypass thermostat is often a puzzle as each vehicle seems to have its own design and location. Sometimes the bypass circuit runs through hoses located outside the engine while others have the bypass located in the block or even the head. Newer engines often incorporate the bypass with thermostat into a rather exotic cast and machined aluminum front cover which can also house the coolant pump. In any case, if the engine thermostat and its associated bypass circuit remains a mystery, the engine's manual should serve as the reference of last resort or call the Evans tech phone line at 610 323 3114 for assistance.