How often to change the oil in my WRX

I simply don't like wasting money needlessly. I stopped doing 3k oil changes 20+ years ago so I've saved a considerable amount of money (a few thousand easily) and also haven't had a single engine issue. So tell me again what 3k oil changes would have done for me. Absolutely nothing but lighten my wallet. I don't have a problem with money because I don't waste it on things like 3k oil changes. I'm 54, retired, and have zero debt.

Also, if I was doing 3k oil changes on both of my cars right now I'd be doing a total of 10 oil changes a year. Not very convenient considering I have to drive to my father's house to do oil changes these days (I live in a condo) With my longer ocis I'm only doing 3 oil changes per year now (1 on the Corvette and 2 on the Honda)

I’m not saying to do a 3k OCI. I’m an advocate for doing up to XXXX miles / 6months, whichever comes first. If you drive enough to put 7k on in 6 months, you’re probably driving enough to get the oil up to temperature and burning off a lot of contaminates. Therefore you would change it every 7k/6months, whichever comes first. That’s still only twice a year per car, not 5-10 times.
It all boils down to the conditions in which the oil and engine are subjected to IMO. Short trips, turbocharged engines, driven hard, GDI,…very hard on oil. If the OP only gets to 3k in 6 months, yet he drives it hard, it sounds like very hard, short trips. Changing the oil every 6 months isn’t going to break the bank and he only has to do it twice a year.
 
The FA engine isn’t as fragile as the EJ was. Even after blowing a turbo on my tuned Forester (it was stock when it blew due to oil screen clogging), I stuck with Euro oils at 5k mile intervals. It did burn oil so replenishing it probably helped.

You’re running two grades above the recommendation and even thicker than the JDM WRX recommends. I would have no problems running an oil to 5k mile intervals even at longer than the six months recommendation, presuming the warranty doesn’t matter since you’re tuned. I would run a C3 oil over a A3 though. If you stick with Amsoil 5W-40 go with the AFL. I would use a lower SAPS oil in a DIT regardless of the brand.

If you get a UOA, I would recommend Oil Analyzer’s Inc or any lab that tests fuel by Gas Chromatography. The fuel dilution reading would be beneficial on a tuned WRX.
 
The FA engine isn’t as fragile as the EJ was. Even after blowing a turbo on my tuned Forester (it was stock when it blew due to oil screen clogging), I stuck with Euro oils at 5k mile intervals. It did burn oil so replenishing it probably helped.

You’re running two grades above the recommendation and even thicker than the JDM WRX recommends. I would have no problems running an oil to 5k mile intervals even at longer than the six months recommendation, presuming the warranty doesn’t matter since you’re tuned. I would run a C3 oil over a A3 though. If you stick with Amsoil 5W-40 go with the AFL. I would use a lower SAPS oil in a DIT regardless of the brand.

If you get a UOA, I would recommend Oil Analyzer’s Inc or any lab that tests fuel by Gas Chromatography. The fuel dilution reading would be beneficial on a tuned WRX.
This.

If I still had one (I had a 2016), I'd be running M1 ESP 5W-30 or 0W-30. Especially now, since the 0W-30 is now stocked at Walmart for $27-29.

Low-SAPS oil and frequent OCIs should help to keep the intake valves clean.

I ran Pennzoil Platinum 10W-30 at no more than 6K OCIs when I had mine, but it wasn't tuned.
 
I have to disagree with Cheesepuff. If using Walmart oil, use a Euro oil (Castrol 0w40, M10w40, QS 5w40, even Pennzoil Euro 5w30…in that order. Don’t know about Valvoline Euro if your Walmart has it). Castrol Euro 5w30 or Euro 5w40 might be OK, but deserve to be called the “Walmart end” of the Castrol Euro product lines.

I still think Amsoil and HPL are generally better, but you have to choose the right one. @Orangepeel do I have this right: you replaced the Amsoil 5w30 Euro with one of the Amsoil 5w40 Euro’s? I wish Pablo had maybe directed you more specifically than just “stick with Amsoil.” If that’s all he did, that wasn’t particularly helpful.

I’m still puzzled by the low viscosity with the high flashpoint in your Blackstone UOA in the other thread. It’s possible a retest would have been justified. They might have botched it. But again, I would switch to Oil Analysers, for your UOA’s or someone else who does gas chromatography, and look for fuel dilution, and keep your 100c viscosity above 10.5 or better yet, 11. If indeed you switched from 5w30 to 5w40 Amsoil Euro, that should do the trick, but so should Amsoil Signature 0w40. I know local Subaru places here would suggest Motul, but the right grade of Amsoil should also be great. I’ve lost track of the various Motul’s, don’t know which is best for direct injected turbo motors, but one Subaru tuner shop here swears by it, as does another track-oriented shop.

My EJ25 is not tuned, and I don’t track it, but I have been known to get on it now and then. I disagree that the EJ engine is more fragile than the F-whatever. Too many random tunes and overstressed driving give it a bad rap. I found Castrol Euro 0w30 to be the best Castrol, with 0w40 Euro being 2nd, but that’s just as unobtanium now. For that matter, Castrol might have “watered down” whatever made their older 0w30 so great. iMHO, the Walmart flavors are lessor. I was going to move to Amsoil or HPL, but couldn’t decide which. I have a small stash of each brand, but all thinner than what I would like to put in the EJ25. Both brands have lots of options, and HPL can get quite pricey. I tried the QSFS, was not that happy, but admittedly, I DIY blended their 5w30 QFFS with their Euro 5w40 as I thought I was going to sell the car within a thousand miles. That didn’t happen. Since I still have it, and found the Castrol 0w30 online, I switched back to it…motor seems quieter, smoother, happier than with the QS. I UOA’d the QS, and it wasn’t terrible, but I still felt like the Castrol and my engine were happier together. The QS lost more viscosity and the iron reading was noticeably higher (my iron was always below 10ppm with the Castrol’s despite running for 4700-5000 mile yearly OCI’s.

***EDIT*** I should probably delete much of this post, but maybe there is still some slightly useful info in it. I keep going into “advice mode” which usually gets me in trouble, and I try to refrain….but I slipped again.

BUT: it would be great if @Orangepeel could clarify a couple things: the other thread came later, and said the UOA was for Amsoil 5w30 Euro. Here, in this thread, he said Amsoil 5w40. In neither case should the UOA 100c viscosity be 9.38, unless significant fuel, or serious shearing (which I would have not expected with Amsoil, though I’ve never used their Euro oils).

Also where are you located? It may not matter, but if you live near Death Valley, recommendations could be different than if you live near Ankorage or Banff.

*******
 
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The FA engine isn’t as fragile as the EJ was. Even after blowing a turbo on my tuned Forester (it was stock when it blew due to oil screen clogging), I stuck with Euro oils at 5k mile intervals. It did burn oil so replenishing it probably helped.
Ahh banjo bolts… 😑
 
Running amsoil at a 40wt is more than enough to run a minimum of 5k intervals with 0 hesitation and 7k+ after a UOA. Driving "hard" on the street with 350 bhp isn't exactly hard on oil.
 
Running amsoil at a 40wt is more than enough to run a minimum of 5k intervals with 0 hesitation and 7k+ after a UOA. Driving "hard" on the street with 350 bhp isn't exactly hard on oil.
My truck is at the ~510rwhp level on E30 and just went 16k on HPL No VII Euro 5w30. That’s a higher power density than the WRX.

Using the right oil is more important than using a heavier grade for a shorter interval.
 
My truck is at the ~510rwhp level on E30 and just went 16k on HPL No VII Euro 5w30. That’s a higher power density than the WRX.

Using the right oil is more important than using a heavier grade for a shorter interval.
The M139 from mercedes makes over 200hp a liter and runs a 0w20 229.71.

The FA and EJ normally run a 40wt after being tuned. Any good tuner will tell you that. Mike G. From Cobb put xcess 5w40 in my Sti after Fbo and a tune.

Point being Amsoil at a 40wt is the correct choice for the FA20.
 
Oh, I’m aware that some engine families seem to need heavier grades under certain operating conditions, especially when outside OEM performance. I’ve had several EJs and still do.

I put a 0w30 in my FA24. A UOA coming this week will show how that held up @ 7500 miles. However, it’s much less stressed than the same oil in my 3.5EB. But neither of those things was my point. Rotella T6 is not the right 40 grade for FA/FBs. Amsoil may well be. There are other options as well.

But I’m willing to bet on pretty good references that those tuners recommending 40 grade oils are because of shortcomings of other oils, not because that engine truly needs a 40 grade when the OEM recommends a 20 grade.
 
Oh, I’m aware that some engine families seem to need heavier grades under certain operating conditions, especially when outside OEM performance. I’ve had several EJs and still do.

I put a 0w30 in my FA24. A UOA coming this week will show how that held up @ 7500 miles. However, it’s much less stressed than the same oil in my 3.5EB. But neither of those things was my point. Rotella T6 is not the right 40 grade for FA/FBs. Amsoil may well be. There are other options as well.

But I’m willing to bet on pretty good references that those tuners recommending 40 grade oils are because of shortcomings of other oils, not because that engine truly needs a 40 grade when the OEM recommends a 20 grade.
EU Manual.
Neither ACEA A3 nor A5 comes in 20 visc. just saying.

For some reason the NA Subarus show up to 5W40. While the turbo only go up to 5W30.

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Oh, I’m aware that some engine families seem to need heavier grades under certain operating conditions, especially when outside OEM performance. I’ve had several EJs and still do.

I put a 0w30 in my FA24. A UOA coming this week will show how that held up @ 7500 miles. However, it’s much less stressed than the same oil in my 3.5EB. But neither of those things was my point. Rotella T6 is not the right 40 grade for FA/FBs. Amsoil may well be. There are other options as well.

But I’m willing to bet on pretty good references that those tuners recommending 40 grade oils are because of shortcomings of other oils, not because that engine truly needs a 40 grade when the OEM recommends a 20 grade.

I’ve been running M1 0w-40 in my FB25 for ~2,000 miles now which has drastically reduced oil consumption to **** near nill.

I know you are speaking in performance/longevity terms and my issue is due to manufacturing flaws but 40 weights do have their place depending on conditions. I do agree just jumping to Rotella fill without proper need is questionable.
 
With fully synthetic oil, vehicles that I am putting on 10,000 miles or more per year, I would do an oil change every 5,000 miles. If I am only putting on 6,000 or 7,000 miles a year, time will be the deciding factor which will probably be about every 6 months or every 3,000 miles or so.
 
My 21 WRX told me today it was due for an oil change I last changed it 12/28/23. I used amsoil 5w40. I've gone 2666 miles. Would you change it now or go longer? The car is stage 1 tuned and I drive it fairly hard. What do you guys think? If I'm only going to go 3k miles or so in 6 months should I even run amsoil? Maybe switch to something else more widely available and change it every 3k? Obviously these engines like to blow up so I'm not trying to press my luck by doing the longest oil change ever. Thanks everyone!
Change it bro! Although my Subaru's aren't built or tuned, I change the oil every April and October. It's easy to remember, and gratifying, also oil is cheap engines aren't. That being said 2666 miles on Amsoil is nothing. Just my opinion buy a cheaper Synthetic Oil, and change it out every 6 months.
 
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