Engine oil FUCHS or OEM Subaru

Either way I have the impression that the engine has a smoother sound and feel now, can this be possibile or it's just a placebo ?

They sell Subaru branded Idemitsu at the parts counter

4.5 L is the Ideal for Mazda 6 2.5 non turbo, I'm from the same country as you. I'm using fuchs titan 5w30 for two years and I recommend you do the same, I noticed quieter engine.

Fuchs Titan GT1 5w30.

Oil being dark is a good indicator that you have to do an oil change. However, you shouldn't wait until it changes color to do it. Clear oil doesn't necessarily mean you can keep going.

It is well established that boxer engines want their oil changed and I do not think for a second that a visual inspection is valid for determining if it is time. Highly, **highly** recommend you change the oil per the manual without hesitation and regardless of what it looks like.

Fuchs is excellent oil, run it in my nismo 370z cause it has specific esters that the cylinder liners need. Don't think it's necessary BMW engines but it is very good quality oil.

I would also make sure that every time you fill up the gas you check the oil dipstick and if it’s a little low top off the oil. In fact, I think this is probably crucial to owning an older Subaru like mine mine has 300 K.

Having had multiple Subarus that leak oil like crazy (they all do when they get old) the leaks are most likely too much for the stop leak additive to fix anyway.

I avoid the 5 minute drive-thru places. One of them wanted over $100 for full synthetic on my Subaru Forester. Not worth the 5 minutes.