# oil viscosity question **URL:** \ **Category:** NYSpeed Automotive\ **Created:** [February 23, 2007, 8:08am UTC](https://forums.speedlife.net/t/oil-viscosity-question/24992 "2007-02-23T08:08:13Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![soopa7fly](https://avatars.discourse-cdn.com/v4/letter/s/c77e96/32.png) [@soopa7fly](https://forums.speedlife.net/u/soopa7fly)\ **Post date:** [February 23, 2007, 8:08am UTC](https://forums.speedlife.net/t/oil-viscosity-question/24992/1 "2007-02-23T08:08:13Z")
whats the difference between 5w-20 and 5w-30? my g/f’s car manual says to use 5w-30 but mobil 1’s website says to use 5w-20. ---
**Author:** ![Zong](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/zong/32/7580_2.png) [@Zong](https://forums.speedlife.net/u/Zong)\ **Post date:** [February 23, 2007, 8:10am UTC](https://forums.speedlife.net/t/oil-viscosity-question/24992/2 "2007-02-23T08:10:39Z")
[http://www.synlube.com/sae5w-20.htm](http://www.synlube.com/sae5w-20.htm) Decent read. ---
**Author:** ![JustinH](https://avatars.discourse-cdn.com/v4/letter/j/9fc29f/32.png) [@JustinH](https://forums.speedlife.net/u/JustinH)\ **Post date:** [February 23, 2007, 9:04am UTC](https://forums.speedlife.net/t/oil-viscosity-question/24992/3 "2007-02-23T09:04:20Z")
read [bobistheoilguy.com](http://bobistheoilguy.com) What kind of car are you thinking of putting 5w20 in? In most cases if its speced for 5w30, then stick with that. All the API SM oils are excellent. You can spend 7 bucks on 5 quarts of walmart brand supertech oil and get excellent protection for most applications. ---
**Author:** ![slasky](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/slasky/32/7408_2.png) [@slasky](https://forums.speedlife.net/u/slasky)\ **Post date:** [February 23, 2007, 9:20am UTC](https://forums.speedlife.net/t/oil-viscosity-question/24992/4 "2007-02-23T09:20:57Z")
I would use what the car’s manual says. Mobil 1 isn’t even a real synthetic anymore. ---
**Author:** ![soopa7fly](https://avatars.discourse-cdn.com/v4/letter/s/c77e96/32.png) [@soopa7fly](https://forums.speedlife.net/u/soopa7fly)\ **Post date:** [February 23, 2007, 9:31am UTC](https://forums.speedlife.net/t/oil-viscosity-question/24992/5 "2007-02-23T09:31:09Z")
its an 06 elantra. her manual says 5w30 and i told her to buy 5w30 but for whatever reason she looked it up on mobil’s website and is asking me why they say 5w20. she doesnt even use mobil 1, she uses castrol syntec i think. ---
**Author:** ![JustinH](https://avatars.discourse-cdn.com/v4/letter/j/9fc29f/32.png) [@JustinH](https://forums.speedlife.net/u/JustinH)\ **Post date:** [February 23, 2007, 9:47am UTC](https://forums.speedlife.net/t/oil-viscosity-question/24992/6 "2007-02-23T09:47:18Z")
Stick with 5w30, any API SM oil would be great. If its in warranty you need to use the oil they spec. If its in warranty you need to change the oil at intervals that they spec. If its out of warranty, I’d run walmart supertech for 5k miles with a supertech filter. ---
**Author:** ![MHill](https://avatars.discourse-cdn.com/v4/letter/m/ea5d25/32.png) [@MHill](https://forums.speedlife.net/u/MHill)\ **Post date:** [February 23, 2007, 2:27pm UTC](https://forums.speedlife.net/t/oil-viscosity-question/24992/7 "2007-02-23T14:27:13Z")
[quote=“Zong,post:2,topic:24992"”] > **[SAE 5W-20 Motor Oil](http://www.synlube.com/sae5w-20.htm)** > > SAE 5W-20 Motor Oil, This article helps you to understand if you should use it in your engine Decent read. [/quote] Very good read. ---
**Author:** ![Violator](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/violator/32/7278_2.png) [@Violator](https://forums.speedlife.net/u/Violator)\ **Post date:** [February 23, 2007, 2:45pm UTC](https://forums.speedlife.net/t/oil-viscosity-question/24992/8 "2007-02-23T14:45:52Z")
Always follor the car manufacturers recommendation. 5W-20 is too damn thin anyway ---
**Author:** ![13005TEDGP](https://avatars.discourse-cdn.com/v4/letter/1/edb3f5/32.png) [@13005TEDGP](https://forums.speedlife.net/u/13005TEDGP)\ **Post date:** [March 4, 2007, 6:12am UTC](https://forums.speedlife.net/t/oil-viscosity-question/24992/9 "2007-03-04T06:12:16Z")
> her manual says 5w30 and i told her to buy 5w30 but for whatever reason she looked it up on mobil’s website and is asking me why they say 5w20. she doesnt even use mobil 1, she uses castrol syntec i think. Grab her by the throat and tell her ur gonna use 5w30 and shes gonna like it. WTF?! My gf has done that before…its like do it yourself then. Sorry, my rant is done. ---
**Author:** ![JustinH](https://avatars.discourse-cdn.com/v4/letter/j/9fc29f/32.png) [@JustinH](https://forums.speedlife.net/u/JustinH)\ **Post date:** [March 4, 2007, 6:29am UTC](https://forums.speedlife.net/t/oil-viscosity-question/24992/10 "2007-03-04T06:29:41Z")
[quote=“Violator,post:8,topic:24992"”] Always follor the car manufacturers recommendation. 5W-20 is too damn thin anyway [/quote] For certain engines that its recommended, it does excellent in used oil analysis reports. I have gotten some excellent results of motorcraft 5w20 in my 98 f150 4.6L with 80k miles.