What is API SP?

Specification · API

API SP is an American Petroleum Institute gasoline-engine oil service category that added protection against low-speed pre-ignition (LSPI), timing-chain wear, and deposits. API SQ is the newer category, but API SP still appears in many manuals; match the category, viscosity grade, and any OEM approval your manual lists.

Specification: API SP
Supersedes: API SN Plus, API SN

Last reviewed June 22, 2026

Check a bottle label

If your manual lists API SP, use the oil spec checker to compare the manual requirement with what an oil bottle says. Need the source first? Start with the owner's manual finder. Viscosity and approvals are separate requirements.

What API SP covers

API SP is a major service category for gasoline-engine oils defined by the American Petroleum Institute. It builds on earlier categories by raising the bar in several areas that matter for modern engines. Among these are protection against low-speed pre-ignition (LSPI), an abnormal combustion event associated with some turbocharged direct-injection designs, along with improved resistance to timing-chain wear and to deposit formation.

Because API tracks these categories with letter codes, you will sometimes see API SP shown inside the API “donut” mark on a container, alongside the viscosity grade. The letter category and the grade describe different things, and both matter when choosing an oil.

API SQ and ILSAC GF-7 are the newer gasoline-oil standards family. If you see SQ/GF-7 on a bottle while your manual lists SP/GF-6, use the API SQ and ILSAC GF-7 explainer and the manual wording before deciding.

How it relates to viscosity

A common point of confusion is treating the API category and the viscosity grade as one and the same. They are not. The viscosity grade — for example 0W-20 or 5W-30 — describes how the oil flows at cold start and at operating temperature. The API category describes the performance and protection level the oil has been tested to meet.

An oil should meet the API category your owner’s manual calls for AND the viscosity grade it specifies. Meeting only one is not enough. Many products list both, so check the label against what the manual asks for.

Compatibility and what to follow

API SP oils are generally suitable in applications that previously called for an earlier API gasoline category such as API SN, provided you use the correct viscosity grade. This kind of backward compatibility is typical for API gasoline categories, but it does not override OEM approvals, warranty wording, or exceptions in your specific manual.

When in doubt, defer to your owner’s manual. It is the authoritative source for which API category and which grade your engine needs, and it accounts for details a general guide cannot.

Frequently asked questions

Is API SP still current?

API SQ is the newer gasoline category introduced with ILSAC GF-7, but API SP remains common on manuals and labels. Use the exact wording your manual requires.

Is API SP backward compatible with older API categories?

API SP oils are generally suitable where an earlier API gasoline category such as SN was specified, in the correct viscosity grade. Confirm any OEM approval, warranty wording, and manual exception before relying on it.

Does API SP tell me the viscosity?

No. The API category and the viscosity grade are two separate things, and an oil must meet both for your engine. Your manual lists each one.

What does the LSPI protection do?

It helps guard against low-speed pre-ignition, an abnormal combustion event seen in some modern turbocharged direct-injection engines. The category sets a performance bar oils must pass.