Changing Differential Oil on the UAZ Bukhanka – Complete Guide with Russian Insights

Keeping your UAZ Bukhanka’s differentials in good condition isn’t just about avoiding breakdowns – it’s about preserving off-road performance and preventing expensive wear. Russian owners often say: “A UAZ’s axles are strong, but only if you feed them clean oil.” Below is a detailed, field-tested guide, combining workshop manual steps with hard-earned tips from Eastern European UAZ forums.

Why differential oil matters

• The front and rear differentials contain hypoid gears that work under high pressure. Without clean, high-quality gear oil, metal-to-metal contact leads to pitting, whining noises and eventual gear failure.
• Old oil also collects condensation, especially after river crossings, turning it milky and reducing lubrication.

Recommended oil type

• Most Russian manuals specify GL-5 gear oil with a viscosity of 75W-90 or 80W-90.
• In severe climates (-30°C winters), many Siberian owners switch to synthetic 75W-90 for better cold-flow.
• For hot summer and heavy load use, mineral 80W-90 is still common.
• Always check for hypoid-gear compatibility.

Service interval

• Factory: every 35,000–40,000 km or once every 2 years.
• Russian off-roaders: after every deep water crossing or 10,000–15,000 km of heavy off-road use.
• If the oil turns cloudy, smells burnt or contains metal particles – change immediately.

Tools & materials needed

• 17 mm square drive or socket for drain/fill plugs (some axles use a 12 mm square – check yours).
• Oil catch pan.
• 2–3 litres of GL-5 gear oil (each diff ~1.3–1.5L).
• Cleaning rag, brake cleaner for plug threads.
• New copper/aluminium sealing washers (optional but recommended).
• Hand pump or oil syringe – filler holes are awkward to reach.

Procedure

1. Warm up the oil
   Drive 5–10 km to warm the differential oil. Warm oil flows better and carries out more contaminants.
2. Access & safety
   Park on a level surface. Engage the parking brake and chock wheels.
3. Locate fill plug first
   Russian mechanics always advise: crack open the fill plug before draining. If you can’t refill, you’ve just created a bigger problem.
4. Drain old oil
   Place the drain pan under the diff. Remove the drain plug and let oil fully drain. Expect a strong smell – hypoid oil is pungent.

5. Clean & inspect
   Clean plug threads and magnet. If threads are damaged or sealing washer is flattened, replace them.
6. Refit drain plug
   Torque to around 35–40 Nm (rear) – Russian users warn against overtightening; the housing threads strip easily.
7. Fill with fresh oil
   Using a hand pump, fill until oil just begins to seep from the fill hole. On level ground, this ensures correct level.
8. Seal & clean
   Refit the fill plug (35–40 Nm). Wipe off any spills – oil attracts dust and dirt.

Russian & Eastern Bloc extra tips

• Breather maintenance: Many Bukhanka owners find the axle breather clogged with mud, causing pressure build-up and oil leaks. Clean or replace it during each oil change.
• Water crossings: If you cross rivers, install extended breather hoses routed above the wheel arches. This reduces water ingress.
• Winter storage: In long, cold winters, some owners overfill the diff slightly to keep bearings submerged – but only if the vehicle stands level.
• After heavy mud runs: Check for mud build-up around the pinion seal. Mud + oil = premature seal wear.
• Mixing oils: Avoid mixing synthetic and mineral GL-5 – Russian forums report foaming and reduced protection in extreme cold.

Signs your diff oil needs urgent change

• Whining or howling sound when accelerating or decelerating.
• Oil leaking from pinion or axle seals.
• Visible metal shavings on drain plug.
• Milky or grey oil (water contamination).

Final check

After your first drive, inspect around drain and fill plugs for leaks. Top up if necessary. Many UAZ veterans keep a half-litre of gear oil in the van for field emergencies.