Another Subaru Blog Post - What should I do to my Subaru?


A few years ago, I realized our community lacks a bit of ground rules, so here's a few things i've put together for you:

- We have lots of new first time owners of Subarus (which is awesome!)
- Lots of misinformation is around
- Many of the new owners are completely ignoring the Subaru needs
- To summarize my point: There's lack of information on maintaing the Subaru motor to last as long as possible.

In this following post, I will try to outline everything I can, include everything I learned and please make sure to read this and submit feedback!

- Coolant
- Fuel

- Transmission fluid (transmission, center and front diff are all in one)
- Rear diff fluid

- What you should know

Engine - YOUR OIL:

From right now, i'll tell you to drop any previous "i've had great experience with brand x, so i'm sticking with it"
Turbocharged Boxer motors are brutal and they will shear any oil that can't handle heat/abuse too well. Your choice of oil will determine your odds of ringlands failure, oil burnt, spun rod bearings, etc etc etc.
The concept with the boxer motors is to use an oil that is able to handle heat and shear as minimum as possible. Porsche approved oils are a go for your Subaru.

Subaru recommends 5w30 for turbo engines and that's due to making their fuel mileage numbers look better...
Wait so does that mean Subaru isn't recommending the best type of oil for the car? Yes and no. 5w30 weight oil will suffice and do the job fine if you're driving from point A to point B with no spirited driving, won't be seeing any AutoX or any track time. Just to leave this here for you, spirited/hard driving puts more load on your motor than an AutoX day - this is important to remember. Higher gears put higher load on the car, AutoX is usually gears 1 and 2 only.

Recommended brands, which have been proven time and time again to be the go-to:

- Shell Rotella T6 0w40 if you're in a cold climate, 5w40 or 10w40 if you're in a hotter climate
- *NEW* - Amsoil now offers 0w40
- Amsoil signature 5w40
- Amsoil signature 10w40
- Mobil 1 0w30 or 5w30 (GERMAN/EUROPEAN SPEC)
- Castrol Edge 0w30 or 5w30 (GERMAN/EUROPEAN SPEC)
- Motul 8000 5w40
- Motul 300v
- Redline 5w40 or 10w40
- Eneos 5w30 or 5w40
- General rule of thumb, any Porsche approved oil is usually very well capable of dealing with our motors. Porsche has a much higher standard for parts and fluids.

Your choice of oil may change during winter vs summer, if you live in a cold climate, 0w30 is gives you a better start up viscosity versus 5w30 or 5w40.

Brands/models to avoid due to bad experiences, direct causation of engine failures:

- Royal Purple
- Mobil 1 USDM spec
- Castrol is iffy under USDM spec, 10w40 seems to farewell, 5w30 is inconsistent
- Gas station oil brands
- High odds of your dealer using bulk oil or department store synthetic oils to keep costs low.

Engine - Coolant:

- Subaru blue coolant is VERY good coolant, I recommend sticking to it.
- Stick to OEM thermostat opening levels unless you live in the middle east or near the equator line.

AVOID: Due to cooling problems time and time again while using such products.

- Additives
- Watter wetters

Engine - Fuel:

Use the best fuel you have available to you! 91Oct (Under the rating of RON+MON/2) is a minimum, 93/94 is highly recommended. If you click here you'll find a data logging table of 91 vs 94.

Drivetrain - Transmission & rear differential fluids

Recommended fluids:
- Subaru Super S fluid
- Redline Shockproof
- Motul gear 300

- Subaru offers 2 options for transmission/rear diff, the regular fluid and the Subaru S (which isn't advertised) you will have to ask for the Subaru S fluid in specific to receive it. In Canada, they run at $17/litre.

- Your dealer *SHOULD* have Subaru S transmission oil, which is a phenomenal synthetic oil and costs roughly the same as other competitors (redline, motul, etc)

- Use the SAME transmission/diff fluid for the entire amount necessary; don't mix brands together to create a "cocktail", each brand have their own formula to their fluid and mixing brand X and brand M together may result in premature failure in the system.


- ANYTHING you do that is power related, understand that you're under the possibility of having your warranty void. In the event which you're under the possibility of such outcome, understand that your dealer HAS TO PROVE your modifications were the DIRECT result of said failure.

- ECU alteration works through resetting the ECU many times over a small period of time, that's usually the indicator of a "modified ECU" - COBB Acessport only resets once, however, it's not invisible or undetectable. When a tuner tunes your car he/she adjust your parameters and reset and log, and repeat until what they see is what they like.

1 comment

  • Great write up! Whether you’re new to Subarus or not, knowing what brands you can trust is a step in the right direction to a lasting engine!

    Understanding correct warm up time is another thing that I believe is important with these boxster engines.

    Jeremy smith

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