Engine oil OEM Mazda or RED LINE

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).

Ran Redline 5w40 when it became purely a summer car in ~2013. ... Not seals are leaking, no issues of any form. Car has been Cobb stage 2 91oct tuned (OTS, not pro-tuned) almost 14 years, with a Crawford v2 AOS, Killer B oil pickup + windage tray being the only reliability mods, and it doesn't burn a single molecule of oil.

Redline is great, used it for years in a track car.

My STI also used it for a while (0w40), but then switched to Rotella.

Redline user have been since I picked up my 04 WRX wagon two years ago. Auto crossed and rally crossed. Works great have had zero issues, also at 170,000 miles on the original engine and still running strong.

I use Redline, similar quality and price to Amsoil, without the MLM BS.

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).

In my experience of trying many different oils, what I think are the best, as far as the engine running cool and smooth shifting are: 1. Redline 15w50

Red Line Racing Two Stroke is the best oil I've run. It leaves a good film and smells the nicest.

I just put Redline 5w-30 into my 2011 STI at the last oil change. We'll see how it goes.

I encountered something similar when I took my CE Turbo in for service a few weeks ago. The invoice said 0W20 and when I asked the service manual why they used the wrong oil they told me “oh our technicians know what oil to use, ignore that.” Needless to say I have zero confidence that the correct oil was used.