Buy 25W-40 Engine Oil

When this design makes sense

Where it never really gets cold, the cold-start half of a viscosity grade is unimportant - and an oil that does not have to cope with low temperatures can be formulated for greater stability in the heat. Grades such as 25W-40 come out of that: intended for warm climates, for stationary engines in heated surroundings and for applications with a steadily high operating temperature.

For a vehicle that stands outdoors through a Central European winter it is the wrong choice. There, oil pressure builds up too slowly after a cold start, and it is in exactly those seconds that most engine wear occurs.

Check the alternatives

If you find 25W-40 in a specification, clarify the operating range: does it apply to use in a warm region or to year-round running in Central Europe? In the second case manufacturers usually name a second, winter-capable grade - often 15W-40 or 10W-40.

For vehicles listed in the oil finder you see the approved oils directly; for units outside the car world, the engine manufacturer's documentation decides.