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KCK infographic comparing 75W-90, 80W-90 and 85W-140 gear oils, explaining SAE J306 viscosity grades, low and high-temperature classifications, and why thicker isn't always better.
4WD Differential Oil

75W-90 vs 80W-90 vs 85W-140: What's the Difference?

Is thicker gear oil really better? Discover the differences between 75W-90, 80W-90 and 85W-140, what the viscosity numbers actually mean, and why choosing the correct gear oil matters more than sim...
KCK infographic explaining how to choose the right differential gear oil by viscosity, GL rating, LSD requirements, gear design and application.
4WD Gear Oil

Can You Put Any Gear Oil in Your Differential?

It says “gear oil” on the bottle. How wrong could you go? More wrong than you think. Discover why viscosity, GL-4, GL-5, LSD requirements, gear design and manufacturer specifications matter when ch...
KCK infographic explaining why gear oil gets hot, covering friction, sliding contact, load, towing, heat, oxidation and severe-duty lubrication.
4WD Gear Oil

Why Does Gear Oil Get So Hot?

Your differential doesn't need to be broken to be cooking its oil. Discover where gear-oil heat comes from, how friction, sliding contact, load and towing affect lubricant life, and why the right f...
KCK infographic explaining what happens inside a differential under load, including hypoid gears, sliding contact, heat, EP chemistry, shock loading and gear wear.
4WD Gear Oil

What Happens Inside a Differential Under Load?

What's really happening inside your differential when you're towing, racing or working it hard? Explore hypoid gears, sliding contact, heat, shock loading and EP chemistry — and why the right gear ...
KCK infographic explaining GL-4, GL-5 and GL-6 gear oil specifications, viscosity, EP chemistry, Limited Slip compatibility and gear oil selection.
4WD Gear Oil

GL-4, GL-5, GL-6 & Gear Oil Specifications Explained

Confused by GL-4, GL-5, GL-6, 85W-140 and all the other numbers on a gear-oil bottle? You're not alone. Learn what these specifications actually mean, why viscosity isn't the whole story, how addit...
Your Gear Oil Doesn't Last Forever
4WD Differential Oil

Your Gear Oil Doesn't Last Forever

Gear oil doesn't suddenly fail the day a differential starts making noise. Discover how heat, load, oxidation, contamination and hard use gradually affect your lubricant — and why regular different...
What Makes a Good Gear Oil?
85W-140 Gear Oil

What Makes a Good Gear Oil?

85W-140 is only the starting point. Discover what really makes a gear oil work, from viscosity and EP chemistry to base oils, Limited Slip compatibility and severe-duty protection.