Mobile One 10-30
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From: Mustang OK
Per your owner's manual and the GM Service Manual, you may use SAE 10W-30 if it’s going to be 0°F (-18°C) or above and the oil meets GM Standard 4718M.
Here's what the 2003 Owner's Manual says. Yours should read much the same:
Following from the 2003 Corvette Owner's Manual, Section 5, Service and Appearance Care:
Hope this helps! 
Here's what the 2003 Owner's Manual says. Yours should read much the same:
Following from the 2003 Corvette Owner's Manual, Section 5, Service and Appearance Care:
What Kind of Engine Oil to Use
Look for two things:
Oils meeting these requirements should also have the starburst symbol on the container. This symbol indicates that the oil has been certified by the American Petroleum Institute (API). You should look for this on the oil container, and use only those oils that are identified as meeting GM Standard 4718M and have the starburst symbol on the front of the oil container. Your vehicle’s engine is filled at the factory with a Mobile 1® synthetic oil. which meets all requirements for your vehicle.
Substitute Engine Oil: When adding oil to maintain engine oil level, oil meeting GM Standard GM4718M may not be available. You can add substitute oil designated SAE 5W-30 with the starburst symbol at all temperatures. If temperatures are above 0°F (-1 8°C), you may substitute SAE 10W-30 with the starburst symbol. Substitute oil not meeting GM Standard GM4718M should not be used for an oil change.
Engine Oil Additives
Don't add anything to your oil. The recommended oils with the starburst symbol are all you will need for good performance and engine protection.
Look for two things:
- GM4718M
Your vehicle’s engine requires a special oil meeting GM Standard GM4718M. Oils meeting this standard may be identified as synthetic. However, not all synthetic oils will meet this GM standard. You should look for and use only an oil that meets GM Standard GM4718M.
Notice: If you use oils that don’t have the GM4718M Standard designation, you can cause engine damage not covered by your warranty.
- SAE 5W-30
As shown in the viscosity chart, SAE 5W-30 is best for your vehicle. However, you can use SAE 10W-30 if it’s going to be 0°F (-18°C) or above. These numbers on an oil container show its viscosity, or thickness. Do not use other viscosity oils such as SAE 20W-50.
Oils meeting these requirements should also have the starburst symbol on the container. This symbol indicates that the oil has been certified by the American Petroleum Institute (API). You should look for this on the oil container, and use only those oils that are identified as meeting GM Standard 4718M and have the starburst symbol on the front of the oil container. Your vehicle’s engine is filled at the factory with a Mobile 1® synthetic oil. which meets all requirements for your vehicle.
Substitute Engine Oil: When adding oil to maintain engine oil level, oil meeting GM Standard GM4718M may not be available. You can add substitute oil designated SAE 5W-30 with the starburst symbol at all temperatures. If temperatures are above 0°F (-1 8°C), you may substitute SAE 10W-30 with the starburst symbol. Substitute oil not meeting GM Standard GM4718M should not be used for an oil change.
Engine Oil Additives
Don't add anything to your oil. The recommended oils with the starburst symbol are all you will need for good performance and engine protection.
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From: Refineryville Texas
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From: San Diego CA
Originally Posted by glerma
Is it okay to use Mobil One 10-30? Literature says to use 5-30 but I am in South Texas (90 degree days)
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Originally Posted by GrayC5
Per your owner's manual and the GM Service Manual, you may use SAE 10W-30 if it’s going to be 0°F (-18°C) or above and the oil meets GM Standard 4718M.
Here's what the 2003 Owner's Manual says. Yours should read much the same:
Following from the 2003 Corvette Owner's Manual, Section 5, Service and Appearance Care:
Hope this helps!
Here's what the 2003 Owner's Manual says. Yours should read much the same:
Following from the 2003 Corvette Owner's Manual, Section 5, Service and Appearance Care:
Hope this helps!
Well, Gray clearly has you covered.
Racer
Joined: Nov 2005
Posts: 416
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From: Centralia Illinois
As I understand multiviscoity oil (5w30) the oil is a weight of 5 when cold and as your engine warms up it thickens to 30 weight. My source is a retired Texaco oil producer. So as for as warm climets you still get 30 weight oil at operating tempature of your engine. Again My opinion I use Mobil I 5w30 and a Mobil I oil filter.
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From: Rehoboth MA . . . NRA Life Member
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Originally Posted by glerma
Is it okay to use Mobil One 10-30? Literature says to use 5-30 but I am in South Texas (90 degree days)
Bob
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Joined: Aug 2001
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From: King George VA
Originally Posted by havesleep
As I understand multiviscoity oil (5w30) the oil is a weight of 5 when cold and as your engine warms up it thickens to 30 weight. My source is a retired Texaco oil producer. So as for as warm climets you still get 30 weight oil at operating tempature of your engine. Again My opinion I use Mobil I 5w30 and a Mobil I oil filter.
Originally Posted by Dave
They are both rated to 30W on the high side, so why bother? If you want protection for prolonged oil temps above 260F (racing conditions), then a 0W-40 offers better protection.
There is some benefit to a 10w30 over a 5w30 in hot climates as the 10w30 will have fewer viscosity improver's and generally better high temp high shear (HTHS) ratings, though some more costly oils like the AMSOIL Series 2000 0w30 buck that general trend. Though increased wear when cold due to the higher viscosity may offset that benefit for a daily driver if the owner isn't careful until the oil is warm. A 0w40 has a lot of VIs to achieve that large spread and if you really want better high temp protection, you should get a 5w40 or a 10w40.
Here are some HTHS ratings pulled directly off the manufacturer's websites all using the same ASTM test:
AMSOIL High Performance 10w40 – 4.3
Mobil 1 EP 10w40 – 3.9
AMSOIL European 5w40 – 3.7
Mobil 1 0w40 – 3.6
AMSOIL Series 2000 0w30 – 3.4 (meets GM Standard 4718M)
Mobil 1 EP 10w30 – 3.21
AMSOIL SAE 10w30 – 3.2 (meets GM Standard 4718M)
AMSOIL SAE 5w30 – 3.2 (meets GM Standard 4718M)
Mobil 1 10w30 – 3.14 (meets GM Standard 4718M)
Pennzoil Platinum 10w30 – 3.1 (meets GM Standard 4718M)
Mobil 1 5w30 – 3.09 (meets GM Standard 4718M)
Mobil 1 EP 5w30 – 3.08
Pennzoil Platinum 5w30 – 3.0 (meets GM Standard 4718M)
Mobil 1 0w30 – 2.99 (meets GM Standard 4718M)
AMSOIL XL 5w20 – 2.7
Mobil 1 5w20 – 2.62
Pennzoil Platinum 5w20 – 2.6
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