Which oil to use? I've read all the posts...
Joined: Jul 2003
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From: Upstate NY
Originally Posted by Bror Jace,Sep 19 2010, 10:33 AM
Truth is, most SL or SM rated 10W-30 oils will work fine in your car for modest intervals.
Winner!!! Unless you plan on putting a million miles on your car, any SL or SM oil will work fine. I used cheap store branded oil in a Toyota Solara for 10 years and 160k miles. Car ran like new when I sold it.
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From: Queen City, NC
Originally Posted by Conedodger,Sep 20 2010, 10:10 AM
Interesting. Honda spec'd 10w-30 for my '03 S2000. Wonder why they would spec 5w-30 for yours? 
Joined: Jul 2003
Posts: 13,471
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From: Upstate NY
Originally Posted by Saki GT,Sep 20 2010, 12:14 PM
Fwiw, these weights are for all practical purposes identical at operating temps. 5W is better for cold starts if you live up north.
redlineracing because he said he uses 5w-30 because it meets the specs. Honda specs 10w-30.
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From: 17 ft below sea level.
Just for fun and laughs!
(or is it.......?)
When all other things are equal the oil with the higher HTHS is the better choice.
The catch is that all things will not be equal when there is a difference in HTHS.
Does this mean everyone should be using 40 or even 50 weights? (high HTHS)
No.
HTHS is important to "protect" and allow oil flow through the engine.
There is a direct and stable relation* between HTHS and oil pressure at operating temp, kinematic viscosity is of less importance.
* What I mean is that for a given HTHS you get a certain oil pressure (& flow), the relation between the 2 is pretty steady.
Cold flow is also important.
5W oils sometimes flow better @ cold temps than 10W, 0W oils always do.
(Except GC, that's close to a 40 weight
)
So 0W oils are what you want.
Bottom line:
Look at the recommended oil, under normal circumstances.
In our case: 10W-30
(No, not 5W-40 that's recommended in the cold!)
What does it mean?
Recommended kinematic viscosity at operating temp = a 30 weight.
The oil you want is a 0W-30.
No way around it
Now look at the specs, the HTHS and the kinematic viscosity (KV)
Find the 0W-30 with the highest HTHS and the lowest KV and that's "The One"
Don't start whining about the price, you wanted the best!
(or is it.......?)
When all other things are equal the oil with the higher HTHS is the better choice.
The catch is that all things will not be equal when there is a difference in HTHS.
Does this mean everyone should be using 40 or even 50 weights? (high HTHS)
No.
HTHS is important to "protect" and allow oil flow through the engine.
There is a direct and stable relation* between HTHS and oil pressure at operating temp, kinematic viscosity is of less importance.
* What I mean is that for a given HTHS you get a certain oil pressure (& flow), the relation between the 2 is pretty steady.
Cold flow is also important.
5W oils sometimes flow better @ cold temps than 10W, 0W oils always do.
(Except GC, that's close to a 40 weight
)So 0W oils are what you want.
Bottom line:
Look at the recommended oil, under normal circumstances.
In our case: 10W-30
(No, not 5W-40 that's recommended in the cold!)
What does it mean?
Recommended kinematic viscosity at operating temp = a 30 weight.
The oil you want is a 0W-30.
No way around it
Now look at the specs, the HTHS and the kinematic viscosity (KV)
Find the 0W-30 with the highest HTHS and the lowest KV and that's "The One"
Don't start whining about the price, you wanted the best!