Quick answer
Castrol coolant in our directory means 5 products from Castrol. The manufacturer names 3 chemistries across them (OAT, IAT, Si-OAT). The spec codes it lists most often are JIS K2234, BS 6580, WSS-M97B44-D. Pick by the spec in your owner's manual, not by brand or colour.
Key takeaways
- 5 Castrol products listed, each linked to its source.
- Forms: Concentrate (3), Premix (ready to use) (2).
- 3 of 5 list at least one OEM or industry spec code.
- Approvals are shown as the manufacturer states them ("meets X per Castrol"), not as our endorsement.
- No prices, ratings or rankings.
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.
| Product | Chemistry | Colour | Form | Spec codes listed | Service life (claimed) |
|---|---|---|---|---|---|
| Castrol ON PG25 | OAT | not published | Premix (ready to use) | 0 | not published |
| Castrol ON PG25T | IAT | not published | Premix (ready to use) | 0 | not published |
| Castrol Radicool NF | not published | not published | Concentrate | 8 | not published |
| Castrol Radicool SF | OAT | not published | Concentrate | 7 | not published |
| Castrol Radicool Si-OAT | Si-OAT | not published | Concentrate | 5 | protects for up to 3 years |
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.
| Spec code (as listed by Castrol) | Family | Products listing it |
|---|---|---|
| JIS K2234 | Japan (JIS) | 3 |
| BS 6580 | British Standard | 3 |
| WSS-M97B44-D | Ford | 2 |
| VW TL 774-F | Volkswagen Group | 2 |
| MB 325.3 | Mercedes-Benz | 2 |
| MAN 324 Typ SNF | MAN | 2 |
| Deutz DQC CB-14 | Deutz | 2 |
| DAF MAT 74002 | DAF | 1 |
| MAN 324 Typ Si-OAT | MAN | 1 |
| MB 325.5 | Mercedes-Benz | 1 |
| VW TL 774-G | Volkswagen Group | 1 |
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.
Not sure which coolant your car takes?
Find your coolant →How to choose a Castrol coolant
- 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.
- 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.
- Open the product page and read the wording. "Approved" is stronger than "meets or exceeds", and both are stronger than "recommended for vehicles requiring".
- 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.
- 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. We add none of our own, and they are not affiliate links. Many retailers block automated checks, so each link is labelled with its check status. We do not show prices.
When to see a mechanic
If you are not sure which coolant your vehicle needs, if the system has been topped up with an unknown coolant, or if you see overheating, coolant loss or a sweet smell, see a qualified mechanic or dealer. See coolant leaks.
Frequently asked questions
What type of coolant is Castrol?
Castrol lists 5 products here. The chemistries named are OAT (2), IAT (1), not published (1), Si-OAT (1). There is no single "Castrol type". Check the product that matches your manual's spec.
What colour is Castrol coolant?
Colours listed: not published. Colour is a dye, not a spec, so match the spec code rather than the colour.
Which Castrol coolant meets JIS K2234?
3 Castrol products list JIS K2234: Castrol Radicool NF, Castrol Radicool SF, Castrol Radicool Si-OAT. Confirm the wording on each product page.
Is Castrol coolant premix or concentrate?
Both forms may exist. Here the forms are: Premix (ready to use) (2), Concentrate (3).
Is Coolant.com affiliated with Castrol?
No. Coolant.com is independent and not affiliated with or endorsed by Castrol. We name the brand only to identify its products.
New to cooling systems? Start with how a car cooling system works. Looking for a product? Search the coolant directory or match your manual's spec with Find my car coolant. See also coolant by car make and coolants by brand.