5W 40 Engine Oil

5W-40 engine oil

5W-40 engine oil is extremely adaptable, handling a wide range of temperatures and maintaining its efficacy both in low winter temperatures and when operating in hotter environments.

What does 5W-40 mean?

“W” stands for winter. The number before the “W” signifies the viscosity of an oil at low temperatures and the number following the “W” indicates its viscosity at normal operating temperatures when the engine is running. The 5 number indicates that the oil is thin at low temperatures and better able to operate in cold start and icy conditions.

Castrol 5W-40 product range

If your engine requires the best 5W-40 synthetic oil, Castrol offers a full range of options across all 3 of our brands – EDGE , MAGNATEC and GTX  - to meet the needs of every driver and vehicle manufacturer.

Castrol 5W-40 product range

Fully synthetic 5W-40 oil

5W-40 synthetic oils use a high quality mineral base oil but have beneficial additives. These additives make the oil more chemically stable, less likely to acidify or oxidise and better able to retain its properties over a longer period of time.

5W–40 synthetic oils are more expensive than mineral oils because they contain more additives. These additives do not just deliver superior engine performance and protection, they also extend the life of the oil meaning that you need to change the oil less often.

5W-40 vs 5W-30

Viscosity measures or numbers refer to a lubricant’s flow rate at low and high temperatures. Fully synthetic  5W-40 engine oils  deliver outstanding performance and protection across a wide temperature range. If you are working with a very powerful engine or operating at higher temperatures with higher loads a 5W-40 will be better suited to your needs than a 5W 30 engine oil .