Anybody regularly run 0-40 in their Subaru n/a 2.5? I was thinking about giving it a try after seeing it in the manual as a possibility. I drive the car almost strictly on the highway...would I be better off sticking with a 30w in this situation?
40wt in Subaru 2.5?
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You should have no problems at all, especially in the summer. Mobil 1 0w40 would be a nice choice. Rotella Syn 5w40 also seems popular with Subie drivers.
Unearthed - The Subaru 2.5 liter naturally aspirated engine is one of the easiest engines on oils.
With straight highway driving, I'd recommend choosing a solid conventional 5w30 oil and running it exclusively. Pennzoil conventional or Castrol GTX 5w30 are both fine choices.
With straight highway driving, I'd recommend choosing a solid conventional 5w30 oil and running it exclusively. Pennzoil conventional or Castrol GTX 5w30 are both fine choices.
+1 Pennzoil Conventional or Castrol GTX
I've seen people say Subaru 2.5l NA engines are very easy on oils, but many used oil analysis, including mine, disagree. Naturally aspirated 2.5l subaru engines tend to shear many 30wt oils down to a 20wt oil by the end of the oci.
To the OP, yes you could run a 40wt, but why? Our motors do tend to shear oil quite a bit, but they do not wear much at all. The only reason I would switch is if you wanted to run extended oci's.
To the OP, yes you could run a 40wt, but why? Our motors do tend to shear oil quite a bit, but they do not wear much at all. The only reason I would switch is if you wanted to run extended oci's.
Sxg6 - Can you point me to your modern Subaru 2.5i UOA showing a sheared quality conventional oil within a normal length UOA under normal driving conditions?
I'm not being facetious, I truly have never seen that. I've seen them shear under longer durations, or tough driving conditions. But even then....we're talking about conventional oils running 6000+ miles and still showing great results overall.
I'm not being facetious, I truly have never seen that. I've seen them shear under longer durations, or tough driving conditions. But even then....we're talking about conventional oils running 6000+ miles and still showing great results overall.
Originally Posted By: JoeFromPA
Sxg6 - Can you point me to your modern Subaru 2.5i UOA showing a sheared quality conventional oil within a normal length UOA under normal driving conditions?
I'm not being facetious, I truly have never seen that. I've seen them shear under longer durations, or tough driving conditions. But even then....we're talking about conventional oils running 6000+ miles and still showing great results overall.
I'm no Sube expert, but that's my impression too. What really sticks in my mind is that set of pics that appeared here a month or two ago depicting the shamefully clean innards of a conventional-fed Sube 2.5 4cyl. That engine sure looked like it was having no problems with non-syn oils.
Sxg6 - Can you point me to your modern Subaru 2.5i UOA showing a sheared quality conventional oil within a normal length UOA under normal driving conditions?
I'm not being facetious, I truly have never seen that. I've seen them shear under longer durations, or tough driving conditions. But even then....we're talking about conventional oils running 6000+ miles and still showing great results overall.
I'm no Sube expert, but that's my impression too. What really sticks in my mind is that set of pics that appeared here a month or two ago depicting the shamefully clean innards of a conventional-fed Sube 2.5 4cyl. That engine sure looked like it was having no problems with non-syn oils.
Any quality 10w30 should work just fine, especially for highway miles: if you want to change it out every 4-5K use a dino or a Blend. If you want to run a substantially longer OCI, use a synthetic.
Very durable engines, nonwithstanding some people's problems with head gaskets in the past.
Cheers!
Very durable engines, nonwithstanding some people's problems with head gaskets in the past.
Cheers!
Most passenger car 0w-40 oils a light 40.
I like a solid 40 weight (~15 cst) in the Forester. Especially with heavy duty use like trailer towing. I also like a dino 30 weight for light duty use (5w winter 10w summer).
I have Formula Shell 10w40 in her now, and some Rotella T 15w40 waiting for the next fill. In the winter it will either get Pennzoil Platinum 5w30 or a 30 weight dino with good cold weather properties like Valvoline or Pennzoil conventional.
I have Formula Shell 10w40 in her now, and some Rotella T 15w40 waiting for the next fill. In the winter it will either get Pennzoil Platinum 5w30 or a 30 weight dino with good cold weather properties like Valvoline or Pennzoil conventional.
Originally Posted By: JoeFromPA
Unearthed - The Subaru 2.5 liter naturally aspirated engine is one of the easiest engines on oils.
With straight highway driving, I'd recommend choosing a solid conventional 5w30 oil and running it exclusively. Pennzoil conventional or Castrol GTX 5w30 are both fine choices.
I agree with Joe. Here's a used oil analysis from my run of Pennzoil Ultra 5w30
https://bobistheoilguy.com/forums/threads/pennzoil-ultra-5w30-2009-subaru-impreza-2-5i-4-000.132536/
You could run a 40wt. I formerly ran Rotella 5w40 and ended up with bad gas mileage. I'm currently running Eneos 5w40 and the gas mileage is the same if not better than the 5w30 from Pennzoil. I have the same exact car as you do, just a 2009. Same engine.
Unearthed - The Subaru 2.5 liter naturally aspirated engine is one of the easiest engines on oils.
With straight highway driving, I'd recommend choosing a solid conventional 5w30 oil and running it exclusively. Pennzoil conventional or Castrol GTX 5w30 are both fine choices.
I agree with Joe. Here's a used oil analysis from my run of Pennzoil Ultra 5w30
https://bobistheoilguy.com/forums/threads/pennzoil-ultra-5w30-2009-subaru-impreza-2-5i-4-000.132536/
You could run a 40wt. I formerly ran Rotella 5w40 and ended up with bad gas mileage. I'm currently running Eneos 5w40 and the gas mileage is the same if not better than the 5w30 from Pennzoil. I have the same exact car as you do, just a 2009. Same engine.
1986 subi(250kmi)/2001 subi/1986 vanagon/1986 vw diesel turbo all use motorcraft 5w20 with the '01 subi having the longer intervals of 6000mi if highway driven not more then 75mph..no noticeable oil consumption yet with 98,000mi on the unit..(Blackstone still recommends that I go to 7-7500mi)
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I'd think for highway driving your engine won't see the performance per cost advantage. You will see more money spent for an oil change. 0W-40 is a good oil and it won't hurt. A 15w40 HDEO works well too. I saw 31-33 MPG on the computer on a road trip last summer and that was less than 10k on the odometer. I've now settled on MaxLife 10w30 because it works in everything I own.
The thick oil thing is a part of Subaru lore, which is why I've been using GC in ours.
However, there is a very good recently posted UOA of a 2.5 NA using Ultra, a not very thick starburst oil, so I wonder.
I suspect that your Subie, or mine, would do perfectly well with a 5w30, although Subaru does allow a wide range of grades for its cars.
However, there is a very good recently posted UOA of a 2.5 NA using Ultra, a not very thick starburst oil, so I wonder.
I suspect that your Subie, or mine, would do perfectly well with a 5w30, although Subaru does allow a wide range of grades for its cars.
i'm trying Rotella basic 15w40 for the first time now. the thing i don't like is it takes 25 min to reach operating temp in 80F ambient in a 350 chevy V8. i'm going back to 5 or 10w30
Go for it. I have a 2009 Forester and run 0w40 at times. Depending on where you live the manual even says you can even use a ridiculous 20w40 or 20w50. I am trying to find the European recommend grade of 10w50 as I live in the South where it does get pretty hot and would like to try a run on it.
Some used oil analysis for the NA 2.5l don't show much, if any shearing, while others show a lot of shear. Going to a high 20wt after 8k is one thing, but on some of these reports the oil is dipping into a 20wt after 3-5k. I wouldn't say our motors are super hard on oil like an STI, but with reports like the ones below, I just can't say our cars are easy on oil.
Acceptable range for a 30wt oil 9.3cSt - 12.5cSt
Acceptable range for a 20wt oil 5.6cSt - 9.3cSt
My used oil analysis - 9.08cSt after 4,300mi
https://bobistheoilguy.com/forums/threads/motorcraft-5w30-2009-subaru-legacy-2-5i-4299mi.126157/
Here are a bunch in one thread
8.90cSt after 7,736
8.99cSt after 6,244
8.97cSt after 4,326
8.85cSt after 4,999
9.22cSt after 3,082
8.98cSt after 3,155
https://bobistheoilguy.com/forums/threads/motorcraft-5w30-2009-subaru-legacy-2-5i-4299mi.126157/
8.26cSt after 7,617
https://bobistheoilguy.com/forums/threads/amsoil-xl-5w30-2007-subaru-outback-2-5i.91734/
Acceptable range for a 30wt oil 9.3cSt - 12.5cSt
Acceptable range for a 20wt oil 5.6cSt - 9.3cSt
My used oil analysis - 9.08cSt after 4,300mi
https://bobistheoilguy.com/forums/threads/motorcraft-5w30-2009-subaru-legacy-2-5i-4299mi.126157/
Here are a bunch in one thread
8.90cSt after 7,736
8.99cSt after 6,244
8.97cSt after 4,326
8.85cSt after 4,999
9.22cSt after 3,082
8.98cSt after 3,155
https://bobistheoilguy.com/forums/threads/motorcraft-5w30-2009-subaru-legacy-2-5i-4299mi.126157/
8.26cSt after 7,617
https://bobistheoilguy.com/forums/threads/amsoil-xl-5w30-2007-subaru-outback-2-5i.91734/
After 5k on T6 I am doing a used oil analysis so I'll post it up.
It will be mostly summer with some WOT and a bit of hard driving here & there. No track use and the engine is performing above rated HP at least for a Forester. Since technically it is a detuned STI block it is actually in spec with that.
I tried 3 oils prior to this but never got a used oil analysis. A local Subie guy put in Amsoil, which turned very thin, very quick and just felt harsh and blah. I am pretty sure it was XLF.
I then had GC in for a short stint before my turbo seals went. After that is was local shops oil at 3k OCI's because it was winter & I was doing ARX at the time. They used Carquest filters so I'm sure it is a bulk Carquest oil. It came out real thin but the car felt much better than the Amsoil. I don't remember the GC so much.
The T6 I have it now feels great, very smooth. I used to have quite the shake at idle sometimes an uneven idle but with T6 no more. I know boxer engines do this but mine was really pronounced at times. I wonder if it had something to do with thinner oil and the cam phasing system.
It will be mostly summer with some WOT and a bit of hard driving here & there. No track use and the engine is performing above rated HP at least for a Forester. Since technically it is a detuned STI block it is actually in spec with that.
I tried 3 oils prior to this but never got a used oil analysis. A local Subie guy put in Amsoil, which turned very thin, very quick and just felt harsh and blah. I am pretty sure it was XLF.
I then had GC in for a short stint before my turbo seals went. After that is was local shops oil at 3k OCI's because it was winter & I was doing ARX at the time. They used Carquest filters so I'm sure it is a bulk Carquest oil. It came out real thin but the car felt much better than the Amsoil. I don't remember the GC so much.
The T6 I have it now feels great, very smooth. I used to have quite the shake at idle sometimes an uneven idle but with T6 no more. I know boxer engines do this but mine was really pronounced at times. I wonder if it had something to do with thinner oil and the cam phasing system.
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