So, what does using a 15W40 viscosity oil mean?

If the maximum temperature in your are is +30 degrees in summer and the minimum is -8 degrees in winter, it means that you have a 10 degree margin in summer and 7 degree margin in winter, which means it is safe to use 15W40 oil in your area.

What about 10W40?

In fact it is hard to find 15W40 nowadays in Istanbul, so I always purchase 10W40 instead. that means I will have protection down to -20 degrees Celsius in the winter.

Heard of 0W40 is the best???

The best according to what?? Do you really think that 0W40 is necessary in your area, or this is only "a friend's" recommendation? 0W40 looks like an "all in one" solution, but it doesn't seem like natural. 0W40 means an oil protects down to -35 degrees in winter and up to +40 degrees in summer. I don't remember such a city.

I reside in Central Europe

If you reside in Europe, in most areas 10W30 (-20 / +30) will be OK because in so many countries, the maximum temp in summer is no more than 20-22 degrees.

The 10W30 - 15W40 combination

If you are not sure about the maximum summer temperature or you think that the margin for the summer is too low, you can use 2 different viscosity for winter and summer. Let's say that

• the minimum temp for your area in winter is: -10 to -15 degrees Celsius and
• the maximum temp for your area in summer is: +26 to +28 degrees Celsius.

A 10W30 oil will be OK for winter because it will protect down to -20 degrees Celsius but you may find "protection up to +30 degrees" insufficient, an may want some extra protection in the summer. You have to use an oil with 40 weight at the summer part this time, not 30. The difference between 10W30 and 10W40 weight oils is that they both protect same in the winter(down to -20 degrees), but the second one protects more in the summer (up to +40 degrees Celsius). But remember, you are now in summer and you don't need an oil which protects down to -20 degrees anymore. So, 15W40 will be OK, too.

The conclusion

In fact there's no conclusion, cause choosing the right motor oil depends on the climatic conditions in your area. The only conclusion that may be is: "only you know the right motor oil". After choosing the most suitable one, you can just try the closest choices.

Erdem Uygar

Tuning Linx