Engine oil Shell or OEM Mazda

10w30 Rotella will cut your oil consumption by 70-80%, ran it in my last Subaru until the clutch went at 234k and running it in my current Subaru

Change the oil with Rotella T6 oil.

I use Shell Helix Ultra 5w30 in my 330i car. It also has BMW Long Life certification. I'm very satisfied with it and would recommend it to you. It also offers good value for money compared to other higher-end brands. You don't get better performance for the money you pay.

We use rotella t-6 5-40. Have put on well over a million miles between our vans and its been good. 10k intervals. We have on a 2019 with 260k. Never had any issues. Still on our original DPF. So it's safe to it's low ash oil.

Shell. Literally makes my vehicles dead silent after every oil change.

10W40 on my 1995 Camry

20W50 on my 2015 Toyota Hiace

I personally am changing my own oil with full synthetic on my 23 2.5T every 6000 km or so. No need other than peace of mind for me. Doing it myself only takes 30 minutes and $35 in oil, filter and crush washer.

For [Naturally-Aspirated Skyactiv engines](https://en.wikipedia.org/wiki/SkyActiv), it is highly recommended that you use Mazda's own(Idemitsu) high molly GF-5 0w-20. [Arguably it is one of the best oil for skyactiv engines](http://www.cleanmpg.com/community/index.php?threads/45295/#post-357910).

I use Shell Helix Ultra 5w40 on my m52b20 E39 and I'm super satisfied

Rotella T6 5w-40. No difference in fuel mileage or anything.

I run the diesel Rotella T6 5w-40. My catalytic converter decided to start throwing P0420 codes around 58k miles and I spoke to a shop that I am going to have tune my car and one of the techs said that they reformulated T6 a few years ago and it has more zinc in it than it used to and that might have had an effect on my cat and it's early demise.