WHAT oil? (once and for all!)

Hello guys,im about to do another oil change on my X6 but i am totally confused on what oil to use once again! i have used castrol edge 5W 30 fully synthetic for years and then tried Mobile super plus 2000 10W 40 and didn't really notice a difference,but the hand book clearly states to use 5W 30 but so so so many people on here use 10W 40.

Is it a good idea to avoid listening to manufactures guide lines and use the 10W 40? even when i call mazda they recommend the 5W 30 but so many on here use 10W 40? i really don't know who is right,the people who designed the car or the people who have driven them for years?

I really cant make my mind up who is right.

any thoughts would be great.
Thank you all.

[wirthensohn]

5W-30 is really a good thing and highly recommended - to support your oil dealer's or garage owner's income...

All these old Mazda engines from the 80s and early 90s were built for that older days standard oil types, 10W-40. That's really enough. With "better" (or let's say more expensive for truth) you will never feel any difference. In fact, there will be no benefit for your engine. It's better to have regular oil changes instead of using an expensive oil.

IMHO: when so many people are using 5W-30, the marketing and the oil lobby have done their jobs excellently

And yes, of course, Mazda-dealers have to recommend 5W-30: they have the nice, amazing, powerful Mazda Dexelia oil. Only the best oil for customers cars... and for profit maximisation on the side of the Mazda dealer, Mazda itself and Mazdas oil producer, TOTAL...

Simply use a good 10W-40, not the cheapest, and anything's fine.

[Mazda RX-7 SA]

I totally agree with wirthensohn.

I wrote already something similar in another thread:

Zitat von Mazda RX-7 SA

If the colour is good and you don't have problems with it, I think no need for a change now.
You can wait. But for sure a change now wouldn't be wrong! So its up to your choice.

I personally using 10W40 instead of the 5W30.
Because 5W30 is too low viscosity in my opinion and more expensive and not needed.
But its not wrong to use that one.

If I'm not wrong, Mazda (not the garage) is specifying 10W40 for the K-series engines.
I think your garage is advising 5W30 because this is now the common oil for Mazdas from all the 20xx years.

regards