When to use Subaru upper engine cleaner?

[PronessDave]

I was planning to use the upper engine cleaner after my service because i lost the small tube thing and have to go get it from somewhere but I heard people saying that it is better to use it before the service so all the dirt and grime can be removed with the oil. Can I still use it after the service or should I just wait till my next service to use upper engine cleaner?

[GTSBoy]

It is called "upper" engine cleaner. Only a tiny fraction of anything moved by it should end up in the oil, so it really shouldn't matter when you do it. If you're paranoid, do it beforehand.

In reality, I'm assuming you're talking about putting it in a RB engine, in which case, they hardly build up anything that will get moved by this stuff anyway. I've put a few cans through my car over the years. Never noticed any difference afterwards.

I'm not recommending against its usage. It's just that it is a Subaru product for a reason. The engines that Subaru intend it for have a significant problem with building up crud in the intake tract because of the design features of the engine. The RB simply doesn't have those features. Other shitty modern engines (ie, almost anything, really) will benefit from this stuff far more than an RB will.

[PronessDave]

On 7/16/2022 at 9:30 PM, PronessDave said:

I was planning to use the upper engine cleaner after my service because i lost the small tube thing and have to go get it from somewhere but I heard people saying that it is better to use it before the service so all the dirt and grime can be removed with the oil. Can I still use it after the service or should I just wait till my next service to use upper engine cleaner?

I should have mentioned that I am using this on my 2002 Subaru Impreza WRX on a EJ205 motor

[The Bogan]

Use it before a service

But, as stated you don't need it

Subaru boxer/Direct Injection benefit from it because they don't have port injection which cleans the valves 

The Boxer in a 85 or BRZ doesn't need it because the have both port and DI

A little throttle body cleaner will suffice if you want to clear our some blow by oil from your throttle body 

[The Bogan]

On 17/07/2022 at 9:35 AM, mlr said:

Use it before a service

Subaru boxer/Direct Injection benefit from it because they don't have port injection which cleans the valves 

The Boxer in a 85 or BRZ doesn't need it because the have both port and DI

A little throttle body cleaner will suffice if you want to clear our some blow by oil from your throttle body 

Edited because you have a WRX

[Duncan]

It did help in the cima (direct injected) once it got up there in age/klm, using it a couple of times sorted an intermittent miss at idle and midrange/full throttle.

 

[Duncan]

Adding to this, because the miss at idle was back in the Cima. While I did change the plugs (why the hell would you have 8 cylinders!)

I also pulled off the throttle body and had a look in the intake....

And the rear of the throttle body was terrible too

Ran a can of upper engine cleaner through it as well as cleaning the throttle body itself and changing the plugs and the idle was good again

 

[morboost]

do wrx's make it between services, I thought once you spin a bearing its time to change oil

Edited April 28, 2023 by morboost
mrt