5W-30 vs 5W-40
Results 1 to 8 of 8

This is a discussion on 5W-30 vs 5W-40 within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; For my first oil change I used Pennzoil Formula Shell 5W-30(manufacturer spec). For my second oil change I was thinking ...

  1. #1
    Moderator rage-wrx's Avatar
    Join Date
    Aug 2010
    Location
    Yonkers/NYC
    Posts
    10,793
    I Support ClubWRX

    5W-30 vs 5W-40

    For my first oil change I used Pennzoil Formula Shell 5W-30(manufacturer spec).

    For my second oil change I was thinking of getting Rotella Shell T6 5W-40 after reading good stuff about it on the interwebs.

    My question is would there be any problems with running the "heavier" 5W-40 vs the company specified 5w-30?Would this compromise performance or gas mileage?
    T0ny
    2011 WRX
    2012 FXT

    The Big 2011/2012 Mod Thread


    Ooh,hang on. That is the throb of a turbocharged flat four engine. A sound which,all over the world,heralds the imminent arrival of a moron - JC.

  2. Remove Advertisements
    ClubWRX.net
    Advertisements
     

  3. #2
    Registered User GarrettKoonsman's Avatar
    Join Date
    Apr 2009
    Location
    CO
    Posts
    2,664
    Should be fine. Lots of us running the T6 in 5W-40
    2003 Midnight Black Pearl WRX Sedan
    200.7 AWHP Protuned Stage 2 at 5400ft above sea level
    Bugeye Mafia Member #225
    Mods
    Pics

  4. #3
    He simply abides. SD_GR's Avatar
    Join Date
    Jul 2002
    Location
    CA, US
    Posts
    22,583
    I Support ClubWRX
    Quote Originally Posted by rage-wrx View Post
    For my first oil change I used Pennzoil Formula Shell 5W-30(manufacturer spec).

    For my second oil change I was thinking of getting Rotella Shell T6 5W-40 after reading good stuff about it on the interwebs.

    My question is would there be any problems with running the "heavier" 5W-40 vs the company specified 5w-30?Would this compromise performance or gas mileage?
    Does the owner's manual specify a 40W as acceptable? In theory you should see slightly decreased MPG but in practice I doubt it. Since your car is new I would follow the manual -- but mine allowed a 40W and yours might too.
    WRX Info Links, Courtesy TheJ
    The world breaks everyone and afterward many are strong in the broken places. Ernest Hemingway
    I lied. I cheated. I bribed men to cover the crimes of other men. I am an accessory to murder. But the most damning thing of all... I think I can live with it. And if I had to do it all over again - I would. Benjamin Sisko
    DISCLAIMER: Opinions expressed are the author's alone and are inherently worthless.

  5. #4
    Moderator rage-wrx's Avatar
    Join Date
    Aug 2010
    Location
    Yonkers/NYC
    Posts
    10,793
    I Support ClubWRX
    Quote Originally Posted by SD_GR View Post
    Does the owner's manual specify a 40W as acceptable? In theory you should see slightly decreased MPG but in practice I doubt it. Since your car is new I would follow the manual -- but mine allowed a 40W and yours might too.
    After reading through the manual again its does say that 40W is acceptable.I have never used 40W.I'm more concerned with cold weather crank.
    T0ny
    2011 WRX
    2012 FXT

    The Big 2011/2012 Mod Thread


    Ooh,hang on. That is the throb of a turbocharged flat four engine. A sound which,all over the world,heralds the imminent arrival of a moron - JC.

  6. #5
    Registered User GarrettKoonsman's Avatar
    Join Date
    Apr 2009
    Location
    CO
    Posts
    2,664
    I live in Colorado, it was -30 last winter and my car started fine with the heavier weight oil. You will be ok
    2003 Midnight Black Pearl WRX Sedan
    200.7 AWHP Protuned Stage 2 at 5400ft above sea level
    Bugeye Mafia Member #225
    Mods
    Pics

  7. #6
    He simply abides. SD_GR's Avatar
    Join Date
    Jul 2002
    Location
    CA, US
    Posts
    22,583
    I Support ClubWRX
    Quote Originally Posted by GarrettKoonsman View Post
    I live in Colorado, it was -30 last winter and my car started fine with the heavier weight oil. You will be ok
    A 5W-30 and a 5W-40 or any 5W-XX will behave the same on cold starts. Their viscosity and so their behaviour will differ once they are up to operating temperature. In most inhabited regions a synth 5W-40 will be OK, since it will behave at least adequately from -10 to +45 or so.
    Last edited by SD_GR; 09-06-2011 at 03:47 PM.
    WRX Info Links, Courtesy TheJ
    The world breaks everyone and afterward many are strong in the broken places. Ernest Hemingway
    I lied. I cheated. I bribed men to cover the crimes of other men. I am an accessory to murder. But the most damning thing of all... I think I can live with it. And if I had to do it all over again - I would. Benjamin Sisko
    DISCLAIMER: Opinions expressed are the author's alone and are inherently worthless.

  8. #7
    Registered User xcEXrdr's Avatar
    Join Date
    Aug 2009
    Location
    Pittsburgh, PA
    Posts
    86
    I've been using Rotella Shell T6 5W-40 for about 25k miles. All my oil analysis have looked great. Seems to have a great number of positive reviews from others (on various forums). Think I'll work on extending my intervals next to get the most out of it.
    Stink-eye Mob #17

    2013 WRX STi Sedan

  9. #8
    Moderator Donkey's Avatar
    Join Date
    Apr 2005
    Location
    Da boonies
    Posts
    6,100
    I Support ClubWRX
    Resident Adviser @ WTF Tuning, LLC
    2002 FORESTER S
    1998 FORESTER S




Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •