Engine Oil with API SP

API SP is the current petrol performance category of the American Petroleum Institute, introduced in 2020. What is new in it: protection against low-speed pre-ignition (LSPI) and against timing chain wear - both of them issues of turbocharged direct-injection engines. It replaces SN and SN Plus and is backwards compatible.

What LSPI is and why it took a new oil category

Low Speed Pre-Ignition is uncontrolled self-ignition of the mixture before the spark, at low engine speed and high load. It produces pressure spikes that can destroy pistons and connecting rods in a very short time, and it mainly affects small, highly boosted petrol engines with direct injection - which is almost everything built as a downsizing engine since the 2010s.

Certain additive constituents in the oil encourage the effect. API SP therefore requires proof that the oil does **not** promote LSPI. On top of that come stricter requirements on timing chain wear and on deposits on pistons and turbocharger.

Who needs API SP

  • modern petrol engines with a turbocharger and direct injection, whatever the brand
  • Japanese, Korean and US vehicles, whose manuals classify by API anyway
  • vehicles specified for SN, SN Plus or older: API SP covers them (backwards compatible)

European manufacturers more often name ACEA classes or numbers of their own. If your manual gives an OEM approval, it takes precedence - API SP on its own does not replace VW 504 00/507 00, for example.

API SP, ILSAC GF-6 and viscosity

ILSAC GF-6 is the specification introduced in parallel by vehicle and oil manufacturers; GF-6A is essentially API SP with fuel-efficiency requirements, GF-6B applies to very thin 0W-16 oils. In practice that means a pack marked "API SP" and "ILSAC GF-6A" is the current standard for petrol engines.

API SP is most commonly found in 0W-20, 5W-30 and 0W-30 - exactly the grades of the engines for which LSPI is relevant. The category itself prescribes no viscosity.

What API SP is not

It is no replacement for a Low SAPS approval. If your vehicle has a petrol particulate filter and the manufacturer calls for ACEA C3, C5 or a number of its own, that is the requirement - many API SP oils are built for it, but not all. And it is no replacement for the diesel categories: for diesels the API C categories (CK-4, FA-4) or the ACEA E classes apply.

And a note for imported vehicles: intervals in US handbooks are given in miles. 5000 miles is roughly 8000 kilometres - read the figure as kilometres and you change the oil needlessly early.

Frequently asked questions

Is API SP better than API SN?

It is the newer and stricter category and covers SN and SN Plus backwards. Where the manual calls for SN you may use SP; not the other way round where SP is expressly required - particularly on turbocharged direct-injection engines, because of the LSPI proof.

Do I need API SP if my car is European?

Only if it says so in the manual. European manufacturers mostly work with ACEA classes and approvals of their own. Many modern oils carry both at once, in which case one product meets both sets of requirements.

What is the difference between API SP and ILSAC GF-6?

API SP describes the engine protection requirements; ILSAC GF-6A adds fuel efficiency to them and is tailored to lower viscosities. In practice both marks appear together on the pack.

Does API SP really protect my turbo engine from damage?

It lowers the risk of pre-ignition, because the additive package has been tested for it - no oil can guarantee it. Together with the right viscosity, intervals you keep to and good fuel, it is the part you can influence.