2020 STI.

E

electricmarquis

Joined
Apr 25, 2020
Messages
22
Location
Ashburn
So comming up on my 2nd oil change. First was factory fill drained at 1000miles. Then the dealer gave me the first change which of course is Subaru Syn 5w-30. This will be drained at the 3000 mile mark. I ordered OEM Subaru filters and went to Wallyworld and found Castrol 0w-40 Euro formula. I heard this would shear to 30wt standards after a few thousand miles. I have searched for UOAs with this oil but found the 0w-30 UOAs. I plan on doing 3000 mile oil changes till about 9k miles. Then doing oil tests to see if it can go to 4-5k, which would be a once a year OCI. This is a garage car, only driven for fun and occasional trip to work.

Any flaws in this plan.

I chose the 0w-40 because its $22 and readily available. The other plan was Motul but cant seem to find it on any shelf around me.

Car is stock and will remain stock. I like all my parts#s to match the factory service manuals.
 
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I had a 2015 WRX before. This car just feels alot more refined in build quality materials. The transmission alone is worth it to me as the WRX 6-spd was junk feeling. The gears felt really short. The FA20dit engine always had some fuel in the UOAs. I have followed Subaru since the Colin days of WRC around 1990
 
That Castrol is Porsche A40 approved and is an excellent choice in an STi. I owned an 07' WRX. Subaru use to recommended using a heavier oil under certain conditions and your 2020 manual probably says the same thing.
The 2.5 STi engine is very long toothed and prefers a thicker oil than a energy conserving 5W30. The old 2.0 bugeye WRX's didn't fare well using 5W30. Awesome car btw!
 
You will likely see less shear if you choose an oil without a huge spread. OW-40 is achieved with pour point depressants and viscosity index improvers. Neither of which are superb lubricants. Quite simply, I've had better long term results with M1 10W-30 than any of the 0W-30/40 oils.

The KTM motorcycle guys using a 5W-50 note that it shears to a 30 in about 1000 miles. Contrast that to the 20W-50 synthetics that hold up for 3000 miles in the same bike.
 
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Just reading all the STI forums on EJ oil issues gives you a headache. Sooooo many opinions and only some with UOAs. You can see 10 peoples EJ with same oil and miles and UOAs all over the place. Almost all from Blackstone. Majority from the enthusiast crowd stay away from Subaru 5w-30 but they are also modded dropping 300-500hp. I just want it to stay stock and last. Plus the 2019+ now have a new piston design with thicker crowns and beefy wrist pin support. This increase the piston weight.

I have the 0w-40 on the shelf. I will use it at 3000, then at 6000 do oil test and every other OCI.
 
You made an excellent choice on oil. STIs love 0w40 and 5w40.

I've owned STI for 14 years now and they've been flawlessly reliable, and my current one has 500hp.. still doesn't even burn oil.

You just have to make sure to keep the rpm up, these cars absolutely HATE low rpm.
 
I see that Mobil 1 has a 0w-40 euro oil also. I would like to see uoa on that with a ej257. That stuff is available at Costco and they do $8-12 off sales per 6 qt case.
 
Edge 0W-40 is a good choice and it shearing to a 30 grade is better than a GF5/RC 5W-30 shearing to a 20 grade, IMO. I switch to Edge 10W-40 HM during the summer because my FXT has been an oil burner for the past ~120k miles. I have no doubt that Edge can handle once yearly OCI's, but make sure you're dealer is ok with the interval since SoA recommends time or miles. 6 months or 6k miles, whichever comes first.

Enjoy the STI!

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Well twice a year is no big deal for me. I have a lift in the garage. The OCI would be like 1000 miles though.....seems like a waste.
 
I'd use 5w-30 ESP and chance once per year. After shearing it is basically the same viscosity as the 0w40 and it is cleaner oil, you will have less carbon buildup.
 
Originally Posted by electricmarquis
I have been told that Mobile 1 5w-30s do not perform well in the ej257 engine and they shear below a 20wt.

I wouldn't use Mobile 1 oil anyway.

But then people hear all sorts of things.
 
Originally Posted by electricmarquis
I have been told that Mobile 1 5w-30s do not perform well in the ej257 engine and they shear below a 20wt.



Mobil 1 and Mobil 1 ESP are not the same thing.
 
Originally Posted by electricmarquis
I have been told that Mobile 1 5w-30s do not perform well in the ej257 engine and they shear below a 20wt.

Most Resource Conserving/GF5 oils shear to a 20 grade in an EJ257. Brand does not matter. Mobil 1 5W-30 ESP, and other ACEA C3 oils, are more popular in the newer DIT WRX because they have a higher HTHS than the GF5 oils.
 
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Originally Posted by bluesubie
Originally Posted by electricmarquis
I have been told that Mobile 1 5w-30s do not perform well in the ej257 engine and they shear below a 20wt.
Most, if not all, Resource Conserving/GF5 oils shear to a 20 grade in an EJ257. Brand does not matter.

I've actually seen next to no evidence on here of viscosity deviations due to mechanical shear. Motorcycles, yes but not passenger vehicles. Most of the UOA on here show fuel dilution not shear.

Back before he got banned the last time, SonOfJoe discussed how stable most good quality VII are and that there generally isn't enough stress in a typical engine to cause shearing of the polymer chains. From what he said and what I've seen "shear" is way overrated here.
 
Originally Posted by kschachn
Originally Posted by bluesubie
Originally Posted by electricmarquis
I have been told that Mobile 1 5w-30s do not perform well in the ej257 engine and they shear below a 20wt.
Most, if not all, Resource Conserving/GF5 oils shear to a 20 grade in an EJ257. Brand does not matter.

I've actually seen next to no evidence on here of viscosity deviations due to mechanical shear. Motorcycles, yes but not passenger vehicles. Most of the UOA on here show fuel dilution not shear.

Back before he got banned again SonOfJoe discussed how stable most good quality VII are and that there generally isn't enough stress in a typical engine to cause shearing of the polymer chains. From what he said and what I've seen "shear" is way overrated here..


Thank you, good point. I actually just commented in a Forester XT uoa that it's difficult to tell how much shear there is with DIT Subaru turbos because of the fuel dilution. Although I believe there may be some Subaru turbo uoa's floating around that show shear and no fuel dilution based on fuel tested via GC. That's off the top of my head but maybe someone could find them between our uoa forum, nasioc, iwsti, etc. if they really want to dig for them. I'll see if I can find any but most Blackstone uoa's on a Subaru will just show .5% on fuel dilution.

I was wondering what happened to SoJ!
 
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Originally Posted by kschachn
I've actually seen next to no evidence on here of viscosity deviations due to mechanical shear. Motorcycles, yes but not passenger vehicles. Most of the UOA on here show fuel dilution not shear.

Back before he got banned the last time, SonOfJoe discussed how stable most good quality VII are and that there generally isn't enough stress in a typical engine to cause shearing of the polymer chains. From what he said and what I've seen "shear" is way overrated here.

:) like...
 
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