If you have ever looked into the arsenal of a professional car mechanic, you have probably noticed among the cans of oil and cans of lubricant containers with the inscription "Nefras". This solvent is an indispensable assistant in car service, but not everyone knows what exactly it is for and how to use it correctly. Some craftsmen use it to degrease parts before painting, others to wash carburetors, and still others even clean electrical equipment with it. At the same time, mistakes in working with nefras can result not only in damaged spare parts, but also in fire or poisoning.
In this article we will analyze all areas of application of nefras in car repair — from preparing the body for painting to cleaning the fuel system. You'll learn which types of solvent are suitable for different applications (and why Nefras-S2 is not always better than Nefras-S4), how to store it correctly, and what can be replaced if you don’t have the original at hand. And also - critical errors, which even experienced masters admit, and how to avoid them.
Spoiler: nefras is able to dissolve not only dirt, but also plastic parts, if you mix up the brand. And this is just one of the pitfalls that await beginners.
What is nefras and why is it indispensable in car service centers?
Nefras (petroleum solvent) is a mixture of hydrocarbons obtained during the distillation of oil. Unlike household solvents (for example, acetone or white spirit), nefras has strictly regulated composition and is divided into grades depending on boiling point and chemical properties. This is what makes it a universal tool for auto repair.
The main advantage of Nefras over other solvents is high degree of purification and the absence of foreign impurities. For example, unlike kerosene, it does not leave greasy marks on metal, and compared to acetone, it is less aggressive to rubber seals. This is why he is chosen for responsible work:
- 🔧 Metal degreasing before welding or painting (even microscopic traces of oil will cause the paint to peel off).
- ⚙️ Washing parts fuel system, hydraulics and transmission (dissolves resins and varnish deposits).
- 🔌 Electrical equipment cleaning from oxides and contact lubricant (does not conduct current after drying).
- 🛠️ Removing old sealants and adhesives (for example, when disassembling an engine or gearbox).
At the same time nefras does not destroy aluminum and non-ferrous metals (unlike alkaline cleaners), which is critical for modern cars with lightweight alloys in their design.
Types of nefras: which one is suitable for car repair
Not all nephrases are equally useful. Car service centers usually use three brands: S2-80/120, S4-150/200 and C50/170. Their differences are in the boiling point and evaporation rate, which determines the scope of application.
| Nefras brand | Boiling point, °C | Scope of application in car service | Features |
|---|---|---|---|
| Nefras-S2 (80/120) | 80–120 | Degreasing before painting, cleaning electronics, washing carburetors | Evaporates quickly and leaves no residue. Dangerous for plastic! |
| Nefras-S4 (150/200) | 150–200 | Washing engine parts, removing sealants, cleaning hydraulic systems | Less aggressive, suitable for long-term soaking of parts |
| Nefras-S50/170 | 50–170 | Versatile: from degreasing to fuel tank cleaning | Medium evaporation rate, optimal for most tasks |
The key mistake of beginners is to use Nefras-S2 for washing plastic parts (such as throttle body or sensors). This solvent literally “eats” ABS plastic and rubber seals in a few minutes. For such tasks it is better to take C4 or specialized cleaners (for example, Liqui Moly Pro-Line Drosselklappen-Reiniger).
Important: Nefras-S2 should absolutely not be used to clean paintwork - it dissolves the base layers of paint, leaving matte spots.
Before using nefras on a new part, test its effect on an inconspicuous area. For example, apply a drop to the inside of the hood and wait 5 minutes.
Degreasing parts before painting: step-by-step instructions
One of the most common scenarios for using nefras is preparing body parts for painting. Even if the surface is visually clean, microscopic traces of silicone polishes, oils or wax remain on it, which lead to paint peeling or fisheye appearance (craters on paintwork).
Nefras degreasing algorithm:
- Cleaning coarse dirt — remove dust and abrasive particles with a damp cloth.
- Solvent application - dampen a lint-free cloth Nefras-S50/170 and wipe the surface in one motion (not in circles!).
- Drying — wait for complete evaporation (5–10 minutes). Nefras-S2 evaporates in 1–2 minutes, but it is better not to use it for paintwork.
- Check — run your finger over the surface: if a “creak” remains, it means the fat has been removed.
Errors that spoil the result:
- 🚫Usage dirty napkins — dust particles scratch the soil.
- 🚫 Circular movements When wiped, they may leave microstrips.
- 🚫 Work in dusty room — particles settle on the degreased surface.
Nefras-S50/170 (not C2) was used|The surface was wiped with a lint-free cloth|No circular movements when degreasing|The room is ventilated (but without a draft!)|The absence of “creaking” after drying was checked-->
⚠️ Attention: Nefras-S2 can dissolve fresh acrylic primer! If applying primer less than 24 hours before painting, use only Nefras-S4 or isopropyl alcohol.
Flushing the fuel system: carburetors, injectors, tanks
Nefras is one of the most effective means for cleaning fuel equipment from resins and varnish deposits. It is used both for carburetor systems (for example, on classic VAZs), and for injection engines.
Carburetors
To flush the carburetor (for example, Solex 21083 or Weber 32/36) use Nefras-S4:
1. Remove the carburetor and disassemble it (disconnect the float chamber, jets).
2. Immerse metal parts in a bath of nefras for 30–60 minutes.
3. Clean the channels copper wire and blow with compressed air.
4. Wash the rubber seals separately (nefras will not damage them, but it is better to use specialized cleaner).
To speed up the process you can use ultrasonic bath with nefras heating to 40–50°C.
Injectors and fuel tanks
Suitable for cleaning injectors and tanks Nefras-S50/170 (less aggressive to plastic elements of the fuel system). Algorithm:
1. Drain the gasoline from the tank.
2. Pour 1–2 liters of nefras and shake (or use washing plant).
3. For injectors: connect them to a cylinder with nefras under a pressure of 3-4 atm and “drive” the liquid for 10-15 minutes.
⚠️ Attention: Nefras does not remove rust out of the tank! This requires specialized converters (for example, ASTROhim Antiruster).
What happens if you pour nefras into the gas tank instead of gasoline?
If you pour pure nefras into the fuel tank, the engine won't start — the solvent has too low an octane number (about 40–50). In addition, nefras:
- Will dissolve deposits in the tank that will clog the fuel filter.
- It will damage the rubber seals of the fuel pump (if it is not fluorine rubber).
- May cause detonation if mixed with gasoline (risk of damage to pistons).
The maximum permissible concentration of nefras in gasoline is: no more than 5% (used for “soft” flushing of the system).
Cleaning electrical equipment: generators, starters, sensors
Nefras is often used to remove oxides and contact grease from electrical equipment. For example, when repairing a generator (Bosch, Valeo) or starter (Denso, Mitsubishi) they cleanse:
- Contact rings and brushes.
- Battery terminals.
- Sensor connectors (mass air flow sensor, diesel sensor, lambda probe).
Important details:
- 🔌 Use only Nefras-S2 or isopropyl alcohol - they do not leave conductive traces.
- 🚫 Don't peel nefrasom ECU boards (electronic control unit) - only alcohol or specialized cleaners (for example, Kontakt 60).
- ⚡ After cleaning, blow off the parts compressed airto remove any remaining solvent.
Example: when cleaning mass air flow sensor (MAF) Apply nefras to a cotton swab and gently wipe the threads of the heating element. Do not touch them mechanically!
Nefras-S2 is the only solvent that can be used to clean immobilizer contacts and ignition key chips (does not damage the chips).
Safety precautions: how to work with nefras without risk to health
Nefras - flammable liquid (flash point of vapors: from −30°C for C2 to +40°C for C4). In addition, its vapors are toxic and can cause dizziness or poisoning if inhaled for a long time. Operating rules:
- Ventilation - work in a well-ventilated area or with an exhaust hood.
- PPE - use nitrile gloves (rubber dissolves in nefras!) and a respirator with a carbon filter.
- Eliminate sources of fire — do not smoke, do not work near heating devices.
- Storage - keep nefras in metal cans with a tight lid, away from direct sunlight.
What to do in case of vapor poisoning:
- 🚑 Take the victim to fresh air.
- 💧 Give him warm water or milk to drink (not soda!).
- 📞 If you lose consciousness, call an ambulance immediately.
⚠️ Attention: Nefras Can't extinguish with water! In case of fire, use powder fire extinguisher or sand. Water will only spread the burning solvent.
How can you replace nefras: alternatives and their disadvantages
If nefras is not at hand, it can be replaced with other solvents, but with reservations:
| Substitute | Suitable for | Disadvantages |
|---|---|---|
| White spirit | Degreasing metal, washing parts | Leaves a greasy film, takes longer to evaporate |
| Isopropyl alcohol (90%+) | Cleaning electronics, degreasing before gluing | Doesn't dissolve heavy resins, dear |
| Kerosene (refined) | Flushing the fuel system, removing sealants | Strong odor, may leave traces |
| Specialized cleaners (ABRO, Liqui Moly) | Carburetors, injectors, brake systems | Expensive, not universal |
For example, for washing throttle valve on Toyota Corolla E150 It's better to take a specialized cleaner (CRC Throttle Body Cleaner), and not nefras - it is more careful with plastic elements and the damper position sensor.
FAQ: Frequently asked questions about the use of nefras in car service centers
Is it possible to wash the oil pan with nefras before installing a new gasket?
Yes, but only Nefras-S4 or C50/170. C2 may damage the rubber gasket. After washing, wipe the surface dry and apply a thin layer sealant Loctite 574 (if required).
Is it true that nefras removes rust?
No, nefras does not dissolve rust — it only removes fat and oil deposits. For rust use converters (for example, Tsinkar) or mechanical cleaning (sandblasting).
Is it possible to dilute nefras with gasoline to flush the fuel system?
It's possible, but no more than 1:1 (50% nefras, 50% gasoline). A higher concentration of nefras can damage the rubber seals of the fuel pump. For modern cars (with EFI) it is better to use ready-made washes (for example, Wynn's Injection System Cleaner).
Which nefras is best for cleaning an automatic transmission from old oil before replacing it?
For automatic transmissions (ZF, Aisin) suitable Nefras-S4. It dissolves varnish deposits and friction material residues, but does not damage teflon seals. Rinse the parts in a bath with nefras for 20–30 minutes, then blow with air.
Why did the paint look like shagreen after degreasing with Nefras?
Reason - insufficient drying or use Nefrasa-S2 on plastic parts. Before painting:
- Allow the surface to dry for at least 15 minutes.
- Use C50/170 for plastic.
- Check the humidity in the room (optimally 50–70%).