PennGrade 1 Hypoid Gear Oil | Full-Synthetic Differential | GL-5 75W-90 (27-7766-6)

PennGrade 1 Hypoid Gear Oil — GL-5, 75W-90 Full Synthetic (1 qt)

A full-synthetic gear oil for hypoid differentials. The synthetic base stock provides better cold-flow characteristics than conventional 80W-90, plus superior shear stability under high load.

Vehicle Fitment

• Hypoid differentials: trucks, hot rods, and modern rear-drive vehicles requiring GL-5 spec
• Cold-flow applications: where 75W-90 performance is preferred over 80W-90 conventional
• Not for VW air-cooled transaxles: VW boxes are GL-4 — use part 27-7729-6 instead

Why Choose PennGrade 1?

PennGrade 1 is the modern brand name for the legendary "Brad Penn" green oil — refined in Pennsylvania from paraffinic crude, long a favorite of vintage and air-cooled engine builders. Made in the USA.

Key Features & Benefits

• Full-synthetic base stock: better cold-flow than conventional 80W-90.
• Superior shear stability: holds viscosity under high load.
• GL-5 protection: extreme-pressure additives for hypoid differential gear sets.

Technical Specifications

• EMPI Part #: 27-7766-6
• Grade: 75W-90
• API: GL-5
• Type: Full Synthetic
• Volume: 1 quart bottle, sold individually (case of 12)
• UPC: 707924571158
• Country of Origin: USA

Frequently Asked Questions

• Can I use this in my VW air-cooled transaxle? No. The VW transaxle is a GL-4 application — GL-5 additives can attack the brass synchros. Use PennGrade 1 GL-4 80W-90 (part 27-7729-6) in a VW box instead.
• Why choose 75W-90 synthetic over 80W-90 conventional? The synthetic base stock offers better cold-flow characteristics and superior shear stability under high load.

Explore Related Categories

Oils & Lubricants · Drivetrain & Transmission · Axles