Independent technical reference
Understand the API, ACEA and manufacturer standards behind modern engine oils—without the jargon.
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Start with the standard
Browse independent organizations or specifications written by vehicle manufacturers.
International and regional classifications for engine performance and oil quality.
OEM requirements designed around specific engines, service schedules and emissions systems.
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The learning path
Start with the owner’s manual and find the required viscosity and specification.
Learn what each organization or manufacturer approval actually requires.
Confirm the oil carries every required claim—viscosity alone is not enough.
Technical library
An ACEA sequence such as C3-23 or A7/B7-23 describes a defined engine-oil performance category, but it does not automatically authorize that oil for every vehicle that appears broadly compatible. Learn how to read ACEA claims, what the suffix means, and why the manufacturer requirement remains decisive.
API GL-4 and GL-5 are often treated as a simple ladder of gear-oil performance. They are not. Learn what the designations were designed to cover, why GL-5 remains the only API gear-lubricant designation in current use, and why the exact vehicle requirement still comes first.
API SQ and ILSAC GF-7 became available in March 2025. This guide explains the relationship between SQ, GF-7A and GF-7B, the API Donut, Starburst and Shield marks, and why the newest general standard does not replace a vehicle maker’s specific oil requirement.
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Oil Specifications for iOS
Keep essential organization and manufacturer oil specifications close at hand on iPhone and iPad.
View on the App StoreBuilt for quick reference