Oil recommandation for 2004 Subaru WRX STi

[Mako]

I know I'm late to the party, but I'd say run a TRUE 30w like Castrol GC for spirited street driving. The M1 30w's are a little thin.

If you track the car, I'd go with a 40w--I like M1 TDT. 50w's seem to get a little too hot, at least in the 2.0L mill.

 

[BuickGN]

Originally Posted By: AndyH
Originally Posted By: BuickGN
Then you've got the 0w crowd for a CA climate.... That's funny.

Not just any 0W-XX oil, but specifically Castrol Syntec 0W-30 which has proven to be a very robust oil and closer to a 40-weight oil than most other 30-weight oils. Perfectly usable in CA, TX, AZ, etc. Granted, you may never need the extreme cold-startability (is that a word?) of GC, but the oil is excellent in the heat of the summer as well. My $0.02, YMMV.


I'm sure it does fine but why not go with something like a synthetic straight 30wt in the warmer climates. That way you have something that will not shear but has the same or better cold flow as a 10w-30 conventional.

 

[d00df00d]

Good call. But you're talking about a top-of-the-line synthetic 30-weight, and those are fairly rare in the scheme of things, aren't they? I don't recall seeing anything at the level of Amsoil ACD at any of my local auto parts stores.

 

[lawdogg]

Just a little insight from another platform. A fellow VR-4 driver ran a UOA on some Mobil 1 0W-40 he tracked (road course) on. According to him, it sheared down to almost a 20 weight in only ~1000 miles and a track day which is very scary.

If you are considering a dino oil, I'm of the opinion that HDEO should be considered. It's very strong even with VII's and has been shown in the UOAs I've seen to not shear while containing good Zn & Ph levels. I'm running 15W-40 HDEO in my VR-4 now, switched from Mobil 1 0W-40; I have no UOAs to show just that my oil pressure is noticeably better under high load / high RPM situations (I do autocross but haven't road coursed).

If you aren't considering a dino oil, I have to suggest Redline / Motul 300V. Both contain great Moly, great Zn & Ph, and have excellent shear strength.

Just some thoughts.

-Ryan

 

[d00df00d]

+1 on the 300V. Dang good stuff, and DEFINITELY shear stable.

 

[gtx510]

Isn't the STI's AVCS controlled by oil pressure?
I'd be worried about a straight weight oil providing too much pressure when cold and adversely affecting the AVCS operation. I've heard the same thing talked about on here in regards to BMW VANOS and it works in a similar fashion.
And can't too much pressure also lead to more bearing wear?

A synthetic SAE 30 is more shear stable than GC???
I'm finding that really hard to believe.
First off, GC starts off thicker than an SAE 30 (~ 12cst vs 10cst).
And a SAE 30's HTHS range is still 2.9-3.5 (like an ACEA A1/A5 oil) and GC's is > 3.5 (like a ACEA A3/B3 oil).
Which one sounds more shear stable?


GC in the winter
5W-40 (M1, Rotella, or better) in the summer

 

[BuickGN]

Originally Posted By: gtx510
Isn't the STI's AVCS controlled by oil pressure?
I'd be worried about a straight weight oil providing too much pressure when cold and adversely affecting the AVCS operation. I've heard the same thing talked about on here in regards to BMW VANOS and it works in a similar fashion.
And can't too much pressure also lead to more bearing wear?

A synthetic SAE 30 is more shear stable than GC???
I'm finding that really hard to believe.
First off, GC starts off thicker than an SAE 30 (~ 12cst vs 10cst).
And a SAE 30's HTHS range is still 2.9-3.5 (like an ACEA A1/A5 oil) and GC's is > 3.5 (like a ACEA A3/B3 oil).
Which one sounds more shear stable?


GC in the winter
5W-40 (M1, Rotella, or better) in the summer


There's temporary and permanent shear. I don't see how it's possible for a straight 30wt to have temporary shear with no VIIs. Look at the ACD's HT/HS which is the same as the GC yet it's quite a bit thinner. Why wouldn't you want a thinner oil with the same HT/HS?

 

[buster]

How does Amsoil 5w30 hold up on these engines?

 

[BuickGN]

Originally Posted By: d00df00d
Good call. But you're talking about a top-of-the-line synthetic 30-weight, and those are fairly rare in the scheme of things, aren't they? I don't recall seeing anything at the level of Amsoil ACD at any of my local auto parts stores.


Agreed, but the price really isn't bad at all, just a hair over $5 a quart (sold in gallons) when I bought it. It's cheap enough that I buy enough for 3 oil changes each time I order so I always have some in stock if I forget to order.

 

[bluesubie]

Originally Posted By: buster
How does Amsoil 5w30 hold up on these engines?

Haven't seen many Amsoil 5W-30 uoa's on modified STI's, although I've seen a few good ones on stock/slightly modified WRX's (both 2.5T).

I just went through one quart of SSO at 3k miles but only used 1 qt. in 8k on my first OCI. I think the Subie turbo's might like a more robust oil. I also think there's some cleaning going on in my engine. This stuff is dark (I know, I know, color doesn't mean anything).

-Dennis

 

[buster]

I would expect the SSO to have high levels of detergents so some cleaning could definitely be taking place. I would stay with it for awhile.

 

[gtx510]

1. Maybe a tribilogist could chime in but in my reading VII's are more related to temporary shear.
http://books.google.com/books?id=gbBQ2pR...num=1&ct=result
http://books.google.com/books?id=cwWgbmL...esult#PPA345,M1

2. Aren't low viscosity oils w/ high HTHS values popular in Nascar and other V8 engines where they are using a high volume oil pump?
There's a high volume (Cosworth?) pump for the sube, but I don't think any model comes with it stock.

3. With Subaru rec'd 5W-40 and 5w-50 oils for warm climates, and all the detonation and spun bearing issues that the STI engine has, a thinner oil would be the last thing I'd use.
In the UOA's that I've looked at GC's used viscosity is still thicker than ACD's new viscosity.
And you still haven't addressed the issue of too much oil pressure during cold starts....

4. ACD is $31.05/gal, $27.95/gal w/ the 10% discount.
That's $6.99/qt PLUS shipping.
Not any cheaper that GC, especially not if Syntec is on sale.
And you can get GC off-the-shelf at almost any Autozone.

 

[BuickGN]

Originally Posted By: gtx510
1. Maybe a tribilogist could chime in but in my reading VII's are more related to temporary shear.
http://books.google.com/books?id=gbBQ2pR...num=1&ct=result
http://books.google.com/books?id=cwWgbmL...esult#PPA345,M1

2. Aren't low viscosity oils w/ high HTHS values popular in Nascar and other V8 engines where they are using a high volume oil pump?
There's a high volume (Cosworth?) pump for the sube, but I don't think any model comes with it stock.

3. With Subaru rec'd 5W-40 and 5w-50 oils for warm climates, and all the detonation and spun bearing issues that the STI engine has, a thinner oil would be the last thing I'd use.
In the UOA's that I've looked at GC's used viscosity is still thicker than ACD's new viscosity.
And you still haven't addressed the issue of too much oil pressure during cold starts....

4. ACD is $31.05/gal, $27.95/gal w/ the 10% discount.
That's $6.99/qt PLUS shipping.
Not any cheaper that GC, especially not if Syntec is on sale.
And you can get GC off-the-shelf at almost any Autozone.


1. That's what I said. Are you implying temporary shear is not a problem in a high performance car?

2. Are you implying a high volume pump is required to run a 30wt? I think a simple oil pressure guage would say differently.

3. Too much oil pressure during cold starts? What's funny is the ACD is thinner at 40c. This is the same paragraph where you recommend a 5w-50 which in reality likely has a higher starting viscosity in any normal ambient temp.

4. So you're paying about the same for inferior GC. What's the hang up about shipping? Is it impossible to plan your oil change 2-3 days in advance? Order on a Monday and it's there in plenty of time for a weekend oil change and delivered to your door.

I'm a fan of thicker oils in performance cars but I don't understand the obsession with 0w oils in mild climates. If it were my car it would have a 15w-40.

 

[edhackett]

GC is an A3 rated oil that has a HTHS of >3.5 and it does not show permanent shear under use. If I remember the analysis Terry had done correctly, it does not contain VII. It achieves its viscosity though the quality of the base stocks.

Here's a 5K UOA from my 2003 WRX. GC is one of the best choices for a turbo Subaru, period.

http://www.bobistheoilguy.com/forums/ubb...true#Post222842

Ed

 

[BuickGN]

Originally Posted By: edhackett
GC is an A3 rated oil that has a HTHS of >3.5 and it does not show permanent shear under use. If I remember the analysis Terry had done correctly, it does not contain VII. It achieves its viscosity though the quality of the base stocks.

Here's a 5K UOA from my 2003 WRX. GC is one of the best choices for a turbo Subaru, period.

http://www.bobistheoilguy.com/forums/ubb...true#Post222842

Ed


From what I remember from a long time ago, it does contain VIIs. I don't see a thick 0w-30 getting that kind of range without them. Look at Redline's VII-less oils and you have 5w-20 and 10w-30. I sort of doubt GC uses a better base stock than Redline.

UOAs are great for measuring how much life is left in the oil but not absolute wear. I could care less about a couple PPM difference, it's meaningless.

 

[d00df00d]

Originally Posted By: BuickGN
Look at Redline's VII-less oils and you have 5w-20 and 10w-30.

I thought 5w-40 was the only one that used VIIs (until the 0w-xx oils came out)?

Plus, Amsoil always bragged about TSO 0w-30 having no VIIs -- and the original formulation had a VI of 194 or something. GC's VI is around 170 IIRC. Doesn't seem improbable at all.


Originally Posted By: BuickGN
I sort of doubt GC uses a better base stock than Redline.

I don't.

Either way, higher VI doesn't necessarily mean it's a better basestock.

 

[BuickGN]

Originally Posted By: d00df00d
Originally Posted By: BuickGN
Look at Redline's VII-less oils and you have 5w-20 and 10w-30.

I thought 5w-40 was the only one that used VIIs (until the 0w-xx oils came out)?

Plus, Amsoil always bragged about TSO 0w-30 having no VIIs -- and the original formulation had a VI of 194 or something. GC's VI is around 170 IIRC. Doesn't seem improbable at all.



Originally Posted By: BuickGN
I sort of doubt GC uses a better base stock than Redline.

I don't.

Either way, higher VI doesn't necessarily mean it's a better basestock.


Really, so you think GC is primarily ester?

I've never looked at or cared to look at TSO but it's kind of hard to believe it had a VI of 194 with no VIIs.

I don't understand what you're trying to imply with Redline. It's VII-less 30wt is a 10w-30. How does GC get a 0w rating on it's heavy 30wt while being VII less?

 

[edhackett]

From the GC Testing thread:

I recieved a copy and it was more info than I can understand, but basically the important stuff to me was-
1. PAO
2. Special esters derived from PAO. Molakule has talked about these in a few threads.
3. No viscoity index improvers. This is why it doesn't shear down.

How do they do it? FM, BuickGN, FM.

Ed

P.S. Sorry for the sketchy details. I'm on 22.8 dial-up out in the sticks, so searching is painful.

 

[d00df00d]

Originally Posted By: BuickGN
Really, so you think GC is primarily ester?

No, I don't. What does that have to do with how good the basestock is?


Originally Posted By: BuickGN
I've never looked at or cared to look at TSO but it's kind of hard to believe it had a VI of 194 with no VIIs.

I agree. I even posted a thread about it WAY back before BITOG changed to the current forum server, and asked Pablo about it point blank. He confirmed that the old 194 VI formulation of TSO had no VIIs.


Originally Posted By: BuickGN
I don't understand what you're trying to imply with Redline. It's VII-less 30wt is a 10w-30. How does GC get a 0w rating on it's heavy 30wt while being VII less?

Well, you seemed to be implying that even the mighty Red Line couldn't formulate anything wider than 5w-20 or 10w-30 without VIIs. What I said was, I thought Red Line formulated ALL their oils without VIIs except the 5w-40 and I guess the new 0w-40. That's what I heard from them when I spoke with them on the phone. That was a while ago, though. Have they gone budget in the past year or so?

What I'm implying is that a VII-less 0w-30 is not as outlandish as you're suggesting.

There have been PAO and ester basestocks with VIs of 200+ for years. That stuff would get you to 0w-30 in a heartbeat.

 

[Solo2driver]

Originally Posted By: peterdaniel


This is a joke and I am asking the moderators to automatically ban anyone that posts this junk with hard core proof.



Hmmmm. I thought this was an open forum where we can post our opinions and experiences regarding oil. Our experiences and opinions differ. Why should that deserve a ban or thread delete?

I'm internally confused, now labeled a "M1 basher" and an avid user at the same time...

Lesson-- use whatever the heck you want in your STi, differing opinions here but in the long run, follow UOA in your engine and watch for trends.