Castrol coolant: products, specs and approvals

Confirm the specification in your owner’s manual before buying. Product examples are not a fitment guarantee.

Castrol coolant at a glance

Castrol products in this directory are made or sold by Castrol. We list 5 of them, 3 car/light-vehicle, 2 data-center. Listed chemistries: OAT (2), IAT (1), not published (1), Si-OAT (1). Listed colours: not published (5). 1 of 5 state a service life, and 3 make a "free of" claim (for example silicate-free or nitrite-free).

These counts describe what Castrol publishes, not how good a product is. A product with no listed spec codes may still meet them. It means the manufacturer did not print them on the page we checked.

Castrol coolant products

Click a product for its full spec table, the manufacturer's exact approval wording, compatibility notes and sources. You can also open several products in Compare coolants.

Chemistries Castrol lists

Chemistry is the inhibitor family that protects the metals in a cooling system. Here is what Castrol names across its products, with a short explanation of each family:

• OAT (2 products): Organic Acid Technology: carboxylate inhibitors, normally silicate- and phosphate-free, used for long service intervals. GM Dex-Cool-type and Ford orange coolants are examples of OAT families.
• IAT (1 product): Inorganic Additive Technology: the traditional silicate- and phosphate-based "green" coolant with shorter change intervals.
• not published (1 product): The manufacturer does not name the inhibitor technology on the source we checked.
• Si-OAT (1 product): Silicated OAT: organic acids with a little silicate. It is the family behind VW TL 774-G (G12++) and similar European specs.

Two products in the same family are not always interchangeable, because additive levels and approvals differ. See OAT vs HOAT vs IAT and G11, G12, G13 and G48.

Specs and approvals Castrol lists

These are the OEM and industry spec codes Castrol lists across its products. Each one reads as "meets [code] per Castrol". The manufacturer's own wording ("approved", "meets or exceeds", "recommended for") is quoted on each product page. A listing is the manufacturer's claim, not an approval by Coolant.com or by the vehicle maker unless the wording says so.

Industry test standards listed: ASTM D3306 (3), ASTM D4985 (3), ASTM D6210 (2). ASTM D3306 covers light-duty glycol coolants, D4985 and D6210 cover heavy-duty coolants, and D8039 covers propylene-glycol fluids for data-center cooling.

How to choose a Castrol coolant

1. Find the spec in your owner's manual (or the label on the coolant reservoir cap). It may be a code such as WSS-M97B44-D, GMW 3420, MS-12106, TL 774-G or MB 325.0, or a named factory coolant.
2. Check whether Castrol lists that exact code. Use the table above, or type the code into Find my car coolant. Letter suffixes matter: TL 774-G is not TL 774-J.
3. Open the product page and read the wording. "Approved" is stronger than "meets or exceeds", and both are stronger than "recommended for vehicles requiring".
4. Choose premix or concentrate. Castrol lists 3 concentrate and 2 premix products here (some are sold both ways). Premix avoids mixing errors; concentrate must be diluted with distilled or deionised water. See premix vs concentrate.
5. Do not mix chemistries. If the system already holds a different coolant, check the mixing checker or flush first. See can you mix coolant?

What Castrol does not publish (on the sources we checked)

We do not fill gaps with guesses. Where Castrol's page or sheet leaves a field out, we mark it "not published":

• chemistry: not published for 1 of 5
• colour: not published for 5 of 5
• freeze point: not published for 4 of 5
• service life: not published for 4 of 5
• data sheet link: not published for 5 of 5

The bottle label, the full data sheet or Castrol's technical helpline may give more detail.

Where to buy Castrol coolant

0 of 5 Castrol product pages here carry retailer links. These are the links Castrol itself shows on its product page, or its official parts store. Where a product has a verified Amazon listing we also show an Amazon link, which is an affiliate link (we may earn a commission). Other links are not affiliate links. Many retailers block automated checks, so each link is labelled with its check status. We do not show prices.

Compare with other coolant brands

Brand matters less than the spec code. If Castrol does not list the code in your manual, check whether ACDelco, BASF, BMW or Arteco does, or search every product at once in Find my car coolant. The full list is in the coolant brands index.