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SubaruOutback.org Founder
2018 Outback Limited 2.5L - 111,000+ miles
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Discussion Starter #1
Well guys I recently changed all my lubricants in my car to synthetic. My choice at this time was Mobil 1 product although I won't be buying any Mobil 1 product any time in the future. I'll go with Castrol or AMSOIL from now on.

Anyway I change my engine oil from Castrol Semi-Syn to Mobil 1 Full Syn, put in Mobil 1 ATF, and switched both differentials to Mobil 1 75-90W. The engine is definately running better on full syn and I highly recommend using a full synthetic oil to anyone in your engine.

Here's the bad thing that I almost saw coming unfortunately, many have told me that Subaru Automatic Transmissions don't like synthetic ATF too well and they were right. Although operations seems to be smoother the transmission "shudders" all the time now (sorry its hard to explain if you don't know what I man by "shudders"). So far I and many others don't like how harsh Subaru's 4AT shifts and unfortunately synthetic ATF doesn't help, it may actually end up hurting it. As far as differentials, well I really can't tell the difference.

So here's my preliminary assessment: I would recommend using a full synthetic oil in your engine. I do recommend that before you switch over to full synthetic that you use a semi-sythetic for one oil change before switching to full syn. Other than the engine I would just keep the factory lubricants in your auto tranny and differentials. If you have a manual transmission I would use a synthetic gear lube, I've had some good experiences with that in the past.
 

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Waiting for my Amsoil order at the moment.
 

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'04 Colorado, '90 Legacy sedan
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I've switched my '02 OB to full syn and my '90 legacy sedan 5 spd to full syn. I really haven't noticed any difference, though, my 14 yr old sedan does seem to shift a bit easier and suddenly a leak developed at the driver side axle shaft. I will stay with it from here on out. I want to use the "Smurf oil" Cobb Tuning talked about for the 5spd and diffs.

Anybody tried the Amsoil in the 4EAT?
 

SubaruOutback.org Founder
2018 Outback Limited 2.5L - 111,000+ miles
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Discussion Starter #4
So far I love how my engine is running with synthetic oil in, I can definately tell the difference as compared to other oil changes in the past. Like I had stated before you really can't tell the difference with the differentials, so I'll probably never change the fluid again other than having a dealer change it for me. The transmission seems to have settled down, I think when I said it had been getting worse the tranny was just getting used to the synthetic ATF. That being said nothing has improved as far as the transmission's performance.

So my verdict still stands, use synthetic oil in your engine but you can probably leave everything else the same ;)
 

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MY12 WRX, MY07 FXT
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Well, your differential's shall like the heat dissipation characteristics of the synthetic, not to mention the load resistance or whatever they call it. But overall, that is a good thing if you don't notice anything bad with the changeover. Brian
 

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2004 Outback Sport
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the OBS now has Mobil1 coursing through its veins. I installed a fumoto valve, and wouldn't wou know it, I can only get the lever portion of the body to face forward. I guess the good part is that the chance of a rock, etc. knocking it open is just about nil. Maybe I'll move it for my ~7500 change.

I think I'll leave the diffs on dino for a while longer though.
 

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I have used Mobil 1 since the first oil change on the OBS and will go with synthetics when the other changes come due. I switched over the Legacy Wagon to synthetics at about 50k and had the tranny and diffs "serviced" with the BG products then started with synthetic fluids. That vehicle has 101k on it now. It is probably due for a tune up and the differentials again come to think of it. I am not willing to have the tranny flushed with that many miles on it.
 

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'02 H6 Sedan - gone :(
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I currently use Castrol Syntec Blend 5w30. I have 40k miles on my '02 H6 sedan and have used Castrol since 1k on the odometer. I'm thinking about switching to Amsoil. Has anyone used Amsoil yet in the H6? Did you do the engine flush?

Hero Boots, how is the tranny doing with the synthetic? Did you do the tranny yourself or did you have the dealer do it?

Thanks.
 

SubaruOutback.org Founder
2018 Outback Limited 2.5L - 111,000+ miles
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Discussion Starter #9
kst8er said:
Hero Boots, how is the tranny doing with the synthetic? Did you do the tranny yourself or did you have the dealer do it?

Thanks.
The tranny is slightly better, although for the cost of the 10 quarts of Mobil 1 ATF... nah its not really worth it IMHO. I would highly recommend having your dealer do this for you, for me at least I don't mess with anything other than an oil change anymore ;)
 

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I'm running 5/30 Neo Oil synthetic and 75/90 in the diffs Neo Oil synthetic. It seems to have freed up the diffs as well. Motor and diffs love the synthetic.

In my last Outback H6 (2nd Gen) with the 4EAT I put Amsoil synthetic in the tranny. Didn't notice any shuddering tho'.
 

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Hi,

I am new to Subaru but have owned 7 Saabs and do most all of the maintenance myself. First off I am a believer in full synthetic motor oils. I use Mobil 1 in all my vehicles first because it readily available and secondly it a very good product. Now to my point : Using a synthetic transmission oil in the manual gearbox may not be a good idea. I would stay with Subaru's recommendation here. I have heard of too many horror stories of guys and gals changing there oil in their manual gearboxes in a Saab to synthetic to have a failure shortly thereafter. If Subaru recommends a synthetic or sells one then go with it but if not be careful.

Just my 2 cents worth

Tom
Cape Cod
 

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What is Subaru's position on synth motor oil? Mazda recommends and uses a "semi-synthetic" in the 6 but while they haven't outright said NOT to use pure synth, my dealer advised me not to use it.

just wondering,
-Peter
 

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I don't think Subaru has any stance pro or con about synthetic motor oil. The Subaru rally teams all use it, but I don't know where they really stand with consumers like us...except the tranny. I think most Subaru mechanics tell people not to put synthetic in their trannies. Brian
 

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Subaru Australia has put out a blurb stating the importance of checking fluids even in the break in schedule as a new motor will burn oil until it wears in.

They suggest you buy a litre container of their genuine Subaru oil for top ups between services during this critical time. I didn't keep the blurb but I do remember seeing a picture of their genuine oil bottle. Written on the bottle was Synthetic Motor Oil and I think 5W/30 weight. I'll get another blurb and check the weight, but it definitely said SYNTHETIC MOTOR OIL on the bottle.
 

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2003 Outback
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I'm another synthetic oil believer! And have been for 10 years....although many non-synthetic lubricants are very much improved in recent years.

I use Mobil 1 oil or Redline full product line.

I just used Redline 5W-40 for 8000 hard miles in our 2003 Outback 5s, and had a great oil analysis report.



As far as the Mobil 1 ATF in a Subaru and shudder.... it may be an issue with friction modifiers.

You could call Dave at Redline Oil and se if Redline has a synthetic ATF for the Subaru.

1-800-624-7958

[email protected]

Red Line Synthetic Oil Corporation
6100 Egret Court
Benicia, California 94510

(707)745-6100
(800)624-7958

Fax (707)745-3214

---------------------

An ester like LubeGard makes ~ may~ allow you to modify the Mobil 1 ATF to Subaru's ATF friction modifier standard, or better.


The LubeGard ATF Protectant made a much needed improvement in the way our Mercedes Turbo Diesel automatic shifted.... now it shifts smoothly.

LUBEGARD庐 ATF PROTECTANT

http://lubegard.com/automotive/trans_atf.html

LUBEGARD庐 Highly Friction Modified-ATF Supplement

http://lubegard.com/automotive/trans_atf_hfm.html

I'd contact them for tech support.


Email us: [email protected]
Addresses:
7930 Occidental S.
Seattle, WA 98108 PO Box 24743
Seattle, WA 98124

Telephone:

* 1-800-333-LUBE(5823)
* 1-206-762-5343
* FAX: 206-762-7989
 

SubaruOutback.org Founder
2018 Outback Limited 2.5L - 111,000+ miles
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Discussion Starter #16
blueskybasin, I do appreciate your input but I myself am not going to be putting any more money toward a problem that most likely won't be solved. Subaru's 4EAT is notorious for all problems just about anyone on this site or any other Subaru site has listed, yes it is really that bad. Well not to say that its some scourge that plagues anyone who has it, but IMO its just a shortcoming that really hasn't acknowledged and probably won't now.

Sorry for the rambling, its just that if I have already used Mobil 1 ATF I honestly don't think that a slightly better (and more expensive) product like Redline will make enough difference to justify the cost, let alone the extra cash I'll have to put forth over what I've already spent.

I'm sure many others will find what you've said useful though ;)
 

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2003 Outback
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I can understand not wanting to spend more money. :)

I talked to LubeGard, and they thought that 1 oz of LubeGard ATF Protectant ( The RED bottle ) per quart of ATF in the transmission might help your problem.

As I said the LubeGard has worked very well for me in our Mercedes Turbo Diesel, and also in a friend's Chevey station wagon.

NAPA usually stocks LubeGard ATF Protectant for $10.50 per bottle


LUEBGARD Automatic Transmission Fluid Protectant the NAPA part # is BK765-2601

----------------

If you don't have a NAPA or Pep Boys near you then:

JC Whitney & Co. Catalog
You can reach them at 312-431-6102 & their part #s are
LUEBGARD Automatic Transmission Fluid Protectant is 81-3828T
 

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'96 Legay Outback
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4eat trans fluid

Hi guys,
I'm new to this forum. But very familiar w/the 4eat as I have a '92 SVX.
Many of the guys on our SVX forum(www.subaru-svx.net) have experienced the same shudder feeling w/our trannys. Many of us have gone to Mobil 1 or Redline because of the heat/cooling problem in early 4eat trannys.
We have found that Lubeguard is a very successful answer to the problem, after you do a fluid change.
Also, doing some tight figure 8's in a parking lot to free up the clutch packs helps alot too.
Just my 2 cents. Hope it helps!
milehibri - Brian
 

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02 OB sport, 2.5, 5MT, WRX seats/catback/rear bar, Hellas, Home Despot CAI and roof rack
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my 2 cents worth

i LOVE synthetics, have ever since i first put em in my air cooled motorcycle....air cooled engines actually run audibly quieter on synth, which tells me measures abt internal friction.

i've also had increased leakage with synth engine oil on Euro vehicles, esp older ones, but never on any of my jap or american vehicles.
 
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