Which oil for Subaru 2.5L?

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Jul 15, 2004
Hey, first post, brand new member here! Just want to say first off that I have been visiting the site for a while and spent countless hours here (after which I want to shoot myself...until I come back for more). You are all nuts, but I like it
. Freaks!

My car is a 2002 Subaru 2.5 TS 5MT with 32500 miles on it. I have a K&N filter.

I drive hard and frequently redline. My drive to work is about 25 miles each way; I take a canyon road so I get some good twisties and really thrash it for about 10 miles. My drive home is all freeway. Sometimes I hit some pretty horrendous stop-and-go, this being in LA, and hot temps in the summer, 90+. No cold temps, though, 40's in the winter.

My first oil change after I got the car at 11000 I used a K&N filter and M1 5/30. It sucked. It was noisy, felt unlubricated, and burned 1/2 a quart in 2500. I changed it at 5000 with a PureOne filter and Valvoline Synthetic Blend. It burned no oil and felt better. I went 4500 or so then used a PureOne and 1 quart Valvoline Synthetic and 4 regular valvoline, and have used that since. All those were 5/30's, except the last one I added almost a quart Valvoline Max Life 20/50
. Just thought I'd use it up.

I am considering trying an extended drain interval with Redline, Amsoil, or possibly Mobil Delvac 5/40 or the SUV stuff. I have 2 Amsoil filters on the way, and the redline 5/40 is the easiest for me to obtain. I ordered a Blackstone sample kit yesterday.

I read a good Blackstone report of a 2.5 Subaru with the Redline 5/40: the guy hammered his car hard and was shooting for 10000 miles with no problems.

What are your guys opinions on this idea? Any recommendations?

I appreciate everyones help and knowledge!

Sweet, a reply! Thanks!

I just read bob's air filter test/comparison. The K&N was prett black, and it is dusty in SoCal...I may change back to a paper filter. There was a noticeable difference when I installed it in the performance of the vehicle (my wife noticed it

I bought the PureOne filters based on articles I found placing them at the top in the area of filtration, not realizing how restrictive they are. Hence, the Amsoil filters. I'll try to find SuperTech, where are they from?

I really wasn't happy with the Mobil1 5/30. Noise, roughness, and amount of oil burned bothered me. I would bet 10-30 won't be much different. Am I wrong?

I also have considered just running Premium Plus filters, which flow great, and a better dino like Chevron Supreme (?) for 4000-5000 OCI. Pretty cheap option.

But I do run hard...
2000 Forester S with 72,000 trouble free miles. I use 5w30 Mobil 1, Purolator Pl14460 or OEM and a PureOne or OEM air filter. My oil analysis on my 5,000 mile oil/filter changes is excellent. ed
poison, the Supertech oil filters are the house brand filters from Walmart believe it or not! They are only $2, but are very well made. Champion Labs makes them, they also make the K&N oil filter, Mobil 1, STP, Ultraguard Gold and a few others.
That is great Eddie, you have a good economical high quality oil change there. Do you have oil consumption with the Mobil1?

Ah, Patman, you had to say Walmart: I hate Walmart. No biggie. They have that synthetic that is supposed to be good to, huh? Hmmm. Maybe I should go.

$10 for an oil filter is fine, but if you can get 90%+ of the performance for 1/5 the price...
Well, if you have purchased Amsoil filters, I don't think you need to run to Wally World right away. I have always found the Pure One oil filters to have excellent construction and ADBV function.

You would probably see significantly less consumption with M1 10W-30 than with the 5W-30.
Hmmm, it would be interesting to try the Mobil1 10/30 just to see if consumption went down.

Thatwouldbegreat, I missed your post somehow
. I saw your UOA, pretty cool.

It will either be Amsoil 5/30 or 5/40 Euro, Redline 5/40, or Mobil1 10/30.
I use in my WRX Amsoil 2000 0w/30 or 3000 5w/30 diesel oil. I autocross quite a bit. Never had a problem in 19000 miles. 5w/40 is a bit heavy and not needed...
lot's of guys get good uoa's with mobil 1. i'm not one of them. i just ran my last bit of m1 for 5000 miles, then changed it for a 50~50 blend of pennzoil synthetic and dino. oil analysis at 5000 miles probably.

previous analysis

these numbers weren't bad in general, but they weren't that good for subies. when my last sample gets back from blackstone we'll see how m1 did with 2/3 the mileage.

b04wagon, what is your OCI?

Tweeker (he-he), I really was unhappy with my car on mobil 1. Maybe it was just because it was 5/30, not 10/30.

A place here in LA called Suby Specialties that is very well respected is anti-synthetic for subarus.

For a long time, Subaru stated in the manual to use dino only, but apparently changed it due to pressure from consumers and who knows what else.

So why would I bother with synthetic? Because I drive hard, frequently redline, frequently drive above 3500 RPMs for extended periods, summers are hot, and there is lots of stop and go while running the air conditioning.

Maybe I underestimate the abilities of dino, but that seems pretty tough to me.

I mentioned using redline 5/40 because of the consumtion of mobil1 5/30. i thought the Redline might not do that in my car.
to Poison: Oil consumption using Mobil 1 5w30+Purolator PL14460 and Purolator (OEM) air filter and 5,000 mile change interval yields about 4-6 oz of oil used per change. I used a measuring cup to get the 4-6 oz amount to bring level up to the full line. ed
The K&N air filters have not always been nice to oil analysis. The Pure one oil filters are flimsy and too restrictive in my opinion. I like K&N oil filters. SuperTech oil filters are even better than Pure One.

I am convinced that 40 wt oil is just too heavy in most applications. I doubt that you need it. Probably won't improve your oil analysis. But it won't hurt and will just you lower fuel efficiency.

Options are a 25% mixture of Mobil 1 15W-50 and 10W-30 Mobil 1. Or maybe a quart of 20W-50 Redline with the Mobil 1 10W-30. Give your choices a try though.

I am currently trying a 50% mixture of 5W-20 and and 10W-30 Redline. I like the idea of mixing Mobil 1 and Redline though because of the higher moly and Esters in the Redline. But I think all that moly in 100% Redline is just not that necessary (Even though that's what I'm doing

BTW I am really happy with the Redline. After 3K miles-my milage has gone up about 1 mpg.(I monitor pretty close). Oil consumption-I visibly can not see any drop in oil level after 3K miles and most of that is trip. The engine seems to be a tad quieter, but that may be perception and not scientific. It will be very interesting to see the the oil analysis as I tend to almost "lug" this car-even though it is an auto. I have had higher lead numbers. And in the interest of determining if the moly has helped I have made every effort to continue to "lug" it-even though I know its bad
. Its the 2L SR20DE engine (145 HP )
Subarus hate synthetic oil. My recent conviction based on extensive personal experience as well as objective oil analysis.

My Subarus love Castrol GTX 10W-30. Smooth as butter, more power, rev easier. Excellent oil analysis results. I have also had good luck with Motorcraft 10W-30.

Dump that K&N filter and get an OEM air filter in there. Much better filtration and no increase in resistance. Subaru OEM filters are of outstanding quality. They are oiled paper type. 60k mile replacement intervals.

Subaru OEM oil filters are also the best. Absolutely no reason in the world to use aftermarket stuff. They are cheap, too.
If you search this site, you'll find that Subaru engines (any of them) seem to do well with just about any type of oil. You see great UOA's with synthetic and also with conventional oils.
Since your engine isn't a turbo, I doubt that I'd bother using Redline in it as your engine isn't really very hard on oil, even if driven hard. Mobil 1 10w30 would be an excellent choice, and it's available at good prices. If you insist on Redline, I'd also recommend using 10w30. It's the best choice for most conditions.
As for oil filters, I agree that the OEM filters are very good. I use them or the Pure One filters on my WRX and my UOA's are fine. I think the contention that the Pure One is too restrictive is simply speculation. Yes, it may not flow as well as some filters, but it does filter better than most. And who's to say the flow is inadequate? Especially when the oil is up to operating temperatures, which is where you'll be driving hard. You don't redline the engine until it's warmed up do you?
Wow, I was out for a couple days and got some great replies, thanks to you all!

vvk, I am thinking about changing back to OEM air filters from the K&N. I didn't realize the OEM's were such good quality; a paper filter that lasts 60k? That seems to be a lot! Isn't a normal interval about 15k for a paper filter?

What was your experience between synthetic and dino in oil analysis on the same cars (if you have such info)?

sprintman, whats your OCI with redline?

harrydog, no, I don't redline when cold
! I sit at least until the revs drop 2-3 minutes, usually, then drive easy for at least 10 more minutes. Of course the stupid Subaru temp guage says its hot in 3 minutes...

It is nice to see that the suby engines are pretty well made and get good uoa's. And that Subaru specs such a good filter as OEM. Good stuff...
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