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Old 05-29-2003, 01:11 AM   #1
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Default 10W-30 vs. 5W-30

I have a quick question on oil. I know 10W-30 is best for my engine, but would it be bad to run with 5W-30 in the spring and summer? The reason I ask is because I got an oil change in February and the sticker they put in my window for May said to use 5W-30. I'd rather have the 10-30 so tried to write over it. If there was a chance they still put in 5W-30, should I expect problems (I got an oil change a couple weeks ago)??

I'd be surprised if they used 5-30 for spring and summer. It says 10W-30 right on the damn oil cap. If this sounds like I'm worrying too much, it probably just is.

Thanks for the help.
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Old 05-29-2003, 01:20 AM   #2
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I just use Mobil 1 synthetic 5w-40....engine runs top notch...except for cursed Code 41...

Smooth as silk my friend
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Old 05-29-2003, 01:21 AM   #3
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Either one is good don't worry.

The only difference between 5w30 and 10w30 is the start up viscosity. 5w30 is a little thinner at start up which is good for very cold climates and motors that have over head cams. Remember in an over head cam motor the cam is twice as far away from the oil pan as in a pushrod type motor so a thinner oil gets to the valvetrain faster to protect it.

Once you get to operating temp 5w30 and 10w30 are pretty much identical. I know there were originaly some concerns over 5w30 not lasting quite as long as 10w30 but I think those have been proven false.


Almost all new cars use 5w30 and if you live in a part of the country that sees temps well below freezing on regular basis then I would recomend using 5w30 all the time anyway. In most of the country with a pushrod type engine 10w30 is just fine so don't worry about it.
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Old 05-29-2003, 01:41 AM   #4
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Good news. I worry too much about my baby, that'* all. Thanks for explaining it better.
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Old 05-29-2003, 12:51 PM   #5
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You use the lighter weight oil in the winter because the cold makes its viscosity(big word) alot heavyer. Then in the summer use the heavy weight because the heat thins it out. Just an explaination.
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Old 05-29-2003, 01:47 PM   #6
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If I'm not mistaken....my oil fill cap is stock and it says sae 5w30. Thats what gm recommends.
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Old 05-29-2003, 01:59 PM   #7
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Quote:
You use the lighter weight oil in the winter because the cold makes its viscosity(big word) alot heavyer. Then in the summer use the heavy weight because the heat thins it out. Just an explaination
Yeah, that'* why I got worried, since the 5w-30 is thinner already, I was worried that it would be too thin for the summer time. I should start doing my own oil changes from now on.
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Old 05-30-2003, 12:40 AM   #8
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Quote:
Originally Posted by bonnie94sse
Quote:
You use the lighter weight oil in the winter because the cold makes its viscosity(big word) alot heavyer. Then in the summer use the heavy weight because the heat thins it out. Just an explaination
Yeah, that'* why I got worried, since the 5w-30 is thinner already, I was worried that it would be too thin for the summer time. I should start doing my own oil changes from now on.
Like I said both 5w30 and 10w30 are all climate oils suited to just about all temps. In really extreme cold, like Nome, Alaska in January, you would only want to use 5w30 or even better 0w30 over 10w30. In 90% of temps 5w30 and 10w30 are interchangable but 5w30 is a little better for OHC motors.

Once 5w30 reaches operating temperature it is identical to 10w30.
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Old 05-30-2003, 12:03 PM   #9
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Hi

If your using dino oil, I'd surely be using 10w-30 right now due to several reasons.

The viscosity often will change downward as the miles are added. As this occurs, other things often happen such as evaporation and sludging. 5W-30 Dino, is almost a useless oil for these reasons alone.

As long as your engine doesn't leak , nor burn oil..I would consider using a quality synthetic for the above issues as well as its overall better stability at high temps.
In the winter, dino can not compete with synthetic cold temp flow characteristics.


I have used Wally 10w-30 synthetic at 3.00/q for years. As long as changed every 3k miles...is a excellent replacement for dino. If you want to go top notch, use M1 10w-30, with a quality filter such as Baldwin, K&N OIL filters, or even Mobil'* own filter.

UNDER NO CIRCUMSTANCES, LEAVE DINO IN LONGER THAN 3000 MILES.
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Old 05-31-2003, 12:54 AM   #10
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