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#1140675 - 04/30/08 03:19 PM Which oil grade should I use? 2004 Subaru Forester
spaceballs Offline


Registered: 04/14/07
Posts: 26
Loc: Dallas, TX
I live in Dallas, and this is my first gas engine vehicle in a while. My diesel truck ran a 5w40 year round, which I felt very comfortable with.

My 04 naturally aspirated Forester [with 103k miles on the clock] runs 5w30 right now, which the Owner's Manual says is OK right up to about 95*. Being as this is TX and it does get a little warmer, what is a better weight oil to run? Is 10w30 enough or should a 10w40 be better for this climate for the summer?

I will just be running dino oil, so I don't want to start a discussion of the best oil brand to use. I am more worried about the weight, and I will be running Castrol or Valvoline or Pennzoil or whatever is on sale at the store when I go to buy oil. I run a 4000 miles OCI or so. I would consider a high mileage oil, but the car doesn't use any oil that I can tell.

Seeing as the car has over 100k miles on it, should I bump the grade up to 10w40? Will I lose any economy running a 10w40 v. the 5w30?
_________________________
2004 Subaru Forester X

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#1140683 - 04/30/08 03:29 PM Re: Which oil grade should I use? 2004 Subaru Fore [Re: spaceballs]
Bill in Utah Offline



Registered: 11/11/02
Posts: 12781
Loc: UT
I'd run 5w-30.

I've used it in my Outback and it gets real hot here and for our trips to Vegas.

Stay with normal oils. No need for the HM...

Take care and welcome!

Bill

PS: You *may* take a hit for the 40wt oil. Not needed IMO..

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#1140685 - 04/30/08 03:32 PM Re: Which oil grade should I use? 2004 Subaru Fore [Re: Bill in Utah]
spaceballs Offline


Registered: 04/14/07
Posts: 26
Loc: Dallas, TX
Bill:
Have you ever noticed your 5w30 shearing down enough that you worry?
_________________________
2004 Subaru Forester X

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#1140687 - 04/30/08 03:33 PM Re: Which oil grade should I use? 2004 Subaru Fore [Re: spaceballs]
Bill in Utah Offline



Registered: 11/11/02
Posts: 12781
Loc: UT
 Originally Posted By: spaceballs
Bill:
Have you ever noticed your 5w30 shearing down enough that you worry?


Nope. My UOAs (when I follow what the MFG states ) have been perfect with even the shearing.

Bill

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#1140732 - 04/30/08 04:11 PM Re: Which oil grade should I use? 2004 Subaru Fore [Re: spaceballs]
SubLGT Offline


Registered: 01/31/06
Posts: 1779
Loc: Idaho
 Originally Posted By: spaceballs
.......Seeing as the car has over 100k miles on it, should I bump the grade up to 10w40? Will I lose any economy running a 10w40 v. the 5w30?


No harm can come from using a PCMO 10W40 in the summer. Or you can use a HDEO like Rotella T 10W30. You may or may not see a decrease in fuel mileage with these oils.

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#1140740 - 04/30/08 04:23 PM Re: Which oil grade should I use? 2004 Subaru Fore [Re: SubLGT]
spaceballs Offline


Registered: 04/14/07
Posts: 26
Loc: Dallas, TX
10w40 is listed in the owner's manual for warmer climates. Will any harm [other than perhaps at the pump] come from using a 40 weight oil?
_________________________
2004 Subaru Forester X

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#1140764 - 04/30/08 04:41 PM Re: Which oil grade should I use? 2004 Subaru Fore [Re: spaceballs]
mechtech2 Offline


Registered: 09/05/06
Posts: 19479
Loc: Chicago Area
No harm using 10-40 in Summertime down there.
But if you are not burning or making noises, I'd stick with the 5-30. Try again in 50,000 more miles.

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#1140768 - 04/30/08 04:44 PM Re: Which oil grade should I use? 2004 Subaru Fore [Re: spaceballs]
INDYMAC Offline


Registered: 07/15/06
Posts: 2326
Loc: Magnolia, TX
Welcome to BITOG spaceballs. Since you are a BITOGer now, never say never! And you might as well start saving up for some UOA's too!

I think 10W30 would work great in Dallas. That's what I use year round in all my vehicles (gas) here in Magnolia. I'd also throw a bottle of Auto-Rx in the first fill of the dino of your choice. You can read all about that product in the oil additive section.
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2013 Toyota Tundra DC 4X4 5.7L FFV
2012 Toyota 4Runner 2WD SR5
2004 Honda S2000

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#1140983 - 04/30/08 08:28 PM Re: Which oil grade should I use? 2004 Subaru Fore [Re: INDYMAC]
bluesubie Offline


Registered: 08/04/03
Posts: 1835
Loc: NJ
Hey, this post looks familiar.


Yeah I think the manual says 10W30 or 10W40 for temps over 0F, right? I know mine says 5W30 preferred for fuel economy and a thicker viscosity is required in hot temps. I think I would go with one of those and then do a uoa.

-Dennis


Edited by bluesubie (04/30/08 08:30 PM)
_________________________
'04 Subaru Forester 2.5XT
Motul X-cess 5W-40 | OEM Honeywell filter

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#1142047 - 05/02/08 12:19 AM Re: Which oil grade should I use? 2004 Subaru Fore [Re: bluesubie]
spaceballs Offline


Registered: 04/14/07
Posts: 26
Loc: Dallas, TX
I just finished up my first clean cycle with Auto-RX and now I am beginning the rinse phase. Since I have over 100k, I am going back to another clean cycle in a bit.

I filled up with Pennzoil 10w40 this morning, and after a few days, I will see if the engine is running any quieter. If it is smoothed out, I may just keep running the 40 weight.
_________________________
2004 Subaru Forester X

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