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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.
Differential Oil: Why It Matters More Than You Think
4WD Differential Oil

Differential Oil: Why It Matters More Than You Think

Your engine oil gets plenty of attention. Your differential oil? Not so much. But behind the scenes, that oil is protecting gears and bearings from heat, pressure and load every time you drive. Fro...