STI recommends 0w-40 and 5w-40. Thoughts?
 

For everyone who does some level of performance driving. How many of you actually run 0w-20.

I just make it simple and go of STI’s Japan website and run 5w-40 for driving season and then 0w-40 for winter. Always open to friendly banter on oil viscosity.

5W-40: https://www.sti.jp/parts/subarubrz_z.../ST98050Z2020/

The highest grade fuel-efficient engine oil for the street. It supports a wide range from street driving to sports driving on the circuit. While considering fuel economy more than enough, we will maintain advanced engine protection performance, viscosity & oxidation stability for a long time in harsh usage conditions.

※ The price listed is the manufacturer's suggested retail price excluding labor.

※ S207, S208, WRX STI TYPE RA-R recommended products

※ BRZ (ZD), LEVORG (VN), LEVORG (VM 1.6L), WRX S4 (VB), FORESTER (SK), IMPREZA SUBARU XV (GT/GK), LEGACY B4/LEGA For CY OUTBACK (BN/BS) customers, we recommend this product (5W-40) for high-load driving such as circuit driving, but for winding driving and city riding, STI performance oil (0W-40) ( Item No.: ST98050Z2000) is recommended.

0W-40: https://www.sti.jp/parts/subarubrz_z.../ST98050Z2000/

It is a 0W-40 high-performance engine oil compatible with fuel-efficient cars (0W engine oil designated cars) created by joint development with Motul. In addition to compatibility with horizontally opposed engines, it also demonstrates excellent performance for versatile applications from everyday life to sports driving.

[First-come-first-served benefits]

Only the first 999 sets come with a carbon oil change plate (MOTUL/STI double name, not for sale). The letters written with oil-based magic disappear with alcohol, so it can be used repeatedly.

※ The price listed is the manufacturer's suggested retail price excluding labor.

※ Please note that it will end without notice as soon as the 999 sets of the first-come-first-served benefits are reached.

※ There is no exchange/repair support for the privilege emblem. Please understand.

※ In high-load driving such as circuits, it deteriorates faster than the conventional 5W-40 (ST98050ST110), so we recommend ST98050ST110 (5W-40) for customers with circuit preferences.


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I replied to your FB post as well

The 0w refers to viscosity at 0°F as far as I know, at higher temperatures than that, it is thicker than 0w20, which I believe you would be most of the time. So if you are not tracking it doesn't add much advantage to run 0w40 in winter. Depending on oil temperature you see and if equipped with pressure sensor, how much pressure you see would help you determine what viscosity suits your needs.

Whatever oil you use, add an oil cooler

I ran my first 3 events (6 track days at maybe 30-40 minutes track time per day) on Subaru 0w20. I asked Subie dealer for 5w30 if it would not affect warranty but techs gave me 0w20 anyway, didn't find out until oil analysis! Just put Redline 5w30 in prior to Watkins Glen this past Monday/Tuesday. Set COMSCC T50 class record, clinched '23 championship :D

Track-only I would probably run 40-weight, but since it sees a lot of street miles daily, I run 5w30 during track season.

Despite insistence of many, this car does not need an oil cooler. Never ran one on my '17 over 80k miles and maybe 50 track days, and it ran 275F indicated at the track every session. Was assuming '23 ran same oil temps, but when I actually paid attention to the gauge at the Glen, it was only getting to just under 270F indicated, call it 265F. No problemo for decent synthetic 30-weight...

I've run 5w40 300V (max 7000 km oil change intervals with both OEM heat exchanger and external oil cooler installed) in my 17' for past 4 years. I did everything with the car - from everyday groccery shopping through time attack to 3000kms road trips to Italy during summer. Never had any issues through last 40 000 kms. I'm planning to do exactly the same with my 23' 86 ;)

What does a different turbo engine have to with these?

I wish 17' BRZs came in EU with "different turbo engine" :( Sadly it didn't.

Just another which oil to use thread in a long history of these threads. And still no one knows what the best oil is.

That's because it depends on usage. Since I don't track my car, I'm completely comfortable using what the Subaru engineers spec'd for the engine.

They put 5w-30 in my car this oil change. I think the techs looked at all the mods and thought I'm using the car harder than just a DD.

That’s why Blackstone labs is your friend. Analysis will let you know how the cars doing.

The BRZ STI in Japan is still naturally aspirated.

Sorry, I see STi and naturally think WRX STi.

With my 2004 WRX I've had the last 11+ years, I've always used 5w-40. The EJ205 is rated for 5w-30, but it's common knowledge by now that 40 weight is the oil to use, even for daily driving. It offers a bit extra protection and likely helps against oil leaks over time (maybe?). Back in the day, people would run 5w-30 and the turbo would "shear" the oil down to act like a 20 weight. Engines would spin bearings. The 40 weight would typically shear down to act like a 30 weight over 3-5k miles, and generally you'd be fine.

Keep in mind this took years for people to figure out with trial and error. We're about 10 years in with these FA20's and now the FA24. I suspect in the future it will be common knowledge to be running 5w-30 in both.

Given that, I've stuck to 0w-20 so far in my 2017, but plan on going to a 5w-30. I think going up two grades to a 40 weight is a bit overkill and there could be tighter tolerances and oil passages that 30 weight might be better suited for. Going up one step to a 30 shouldn't be too nuts.

For you winter-climate folks, this applies to you too. The first number probably should be 0 with the new FAs to keep cold starts in freezing temps the same as stock. The second number only applies once the oil is warm, which shouldn't come to play for winter street driving. The engine should be ~200 degrees, so outside temperatures shouldn't really be affecting this.

Just my 2 cents.

Same for me, 5w40 in my 2004 WRX wagon that I bought new May 23, 2003. 156k miles and still a blast.