# Oil weight matter? **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [October 22, 2008, 12:15am UTC](https://community.cartalk.com/t/oil-weight-matter/21034 "2008-10-22T00:15:47Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![mydogmabel](https://avatars.discourse-cdn.com/v4/letter/m/8491ac/32.png) [@mydogmabel](https://community.cartalk.com/u/mydogmabel)\ **Post date:** [October 22, 2008, 12:15am UTC](https://community.cartalk.com/t/oil-weight-matter/21034/1 "2008-10-22T00:15:47Z")
after changing the oil in my sons 2004 neon i noticed on the oil cap it says to use 5w-30 and i used 10w-30. am i in trouble? ---
**Author:** ![Xebadaih](https://avatars.discourse-cdn.com/v4/letter/x/d07c76/32.png) [@Xebadaih](https://community.cartalk.com/u/Xebadaih)\ **Post date:** [October 22, 2008, 12:30am UTC](https://community.cartalk.com/t/oil-weight-matter/21034/2 "2008-10-22T00:30:19Z")
No it won’t cause trouble really. But in the future 5w-30 really should be used, especially in the winter months. ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [October 22, 2008, 12:45am UTC](https://community.cartalk.com/t/oil-weight-matter/21034/3 "2008-10-22T00:45:20Z")
Depends on how cold it gets. I’d rather have a 5 Winter weight oil in the engine than a 10 Winter weight. Afterall, it’s the cold start that wears the engine. Tester ---
**Author:** ![Whitey](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/whitey/32/24680_2.png) [@Whitey](https://community.cartalk.com/u/Whitey)\ **Post date:** [October 22, 2008, 1:05am UTC](https://community.cartalk.com/t/oil-weight-matter/21034/4 "2008-10-22T01:05:45Z")
No, you are not in trouble. The owner’s manual probably says both 5W30 and 10W30 are acceptable oils to use. The 5W30 will give you slightly better fuel economy and will perform better in cold climates, but the 10W30 should not have harmed the car. Still, I would switch to 5W30 next time. Keep in mind the first number (the 5 or the 10) represents the weight (or viscosity) of the oil when it is cold and the second number (30) represents the weight of the oil when it is hot. So both oils have the same viscosity when the engine is warm. ---
**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\ **Post date:** [October 22, 2008, 1:48am UTC](https://community.cartalk.com/t/oil-weight-matter/21034/5 "2008-10-22T01:48:03Z")
Check the manual, likely not a problem - where do you live? ---
**Author:** ![Manolito](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/manolito/32/3070_2.png) [@Manolito](https://community.cartalk.com/u/Manolito)\ **Post date:** [October 22, 2008, 2:04pm UTC](https://community.cartalk.com/t/oil-weight-matter/21034/6 "2008-10-22T14:04:00Z")
The comments from others are all right on the money. Although you are probably fine with this oil in this car, I would just add that modern cars use oil as a coolant as well as a lubricant, so using oil that is a greater viscosity than recommended will void the warranty. A friend was once called to give expert testimony in a lawsuit against Mazda for voiding a warranty due to wrong oil viscosity being used. Mazda won the case. ---
**Author:** ![mcparadise](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mcparadise/32/32_2.png) [@mcparadise](https://community.cartalk.com/u/mcparadise)\ **Post date:** [October 22, 2008, 2:31pm UTC](https://community.cartalk.com/t/oil-weight-matter/21034/7 "2008-10-22T14:31:23Z")
No trouble, but next time you change the oil use 5W-30.