My wives Aztec has 32,000 miles on the odometer. The break in oil up to the first 3,000 miles was Mobil Drive Clean then I switched to Mobil 1 ever since. My question is in the winter months I always use Mobil 1 5w-30 but, in the summer I use Mobil 1 10w-30 should I stick to this or should I go by the manual which says 5w-30? I freak a little since motors nowadays have such close internal clearances.
Mobil 1 5w-30 or 10w-30 in 2003 Pontiac Aztec
- Thread starter Rob Taggs
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The engine aren't a whole lot different, the tolerance are basically the same.
Yes you can run 10w30 in your Aztec as long as the temperature dont fall below 0 F, READ THE MANUAL !!!!
Yes you can run 10w30 in your Aztec as long as the temperature dont fall below 0 F, READ THE MANUAL !!!!
JHZR2
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These days? I guess you mean in the last 30 years?
I recall some discussions on here where people with access to engine spec and shop manuals have described the tolerances in major parts. They have stated that tolerances have not changed in many years, despite manfacturers going to thinner oils; that there was no correlation.
Dont worry about the lower number, thaqt is the winter spec. The lower that number is, the faster flow youll get when it is real cold. However, 5 vs. 10w- oils arent really an issue, as both are so thick compared to their viscosity at operating temperature, that either will give an adequate protection in most any climate.
GM puts in the 5w-30 oil now because it slightly increases fuel economy and reduces pollution at cold startup. They allow 10w-30 at temperatures over some level (I think 0F), which is smart, because if its that cold, then the 5 vs. 10w comes into play.
It probably also says that 5w-30 is preferred year round. Thats what Id use, unless it gets real hot, say over 100F all the time where you live. If so,then change to 10w-30 for those times.
JMH
I recall some discussions on here where people with access to engine spec and shop manuals have described the tolerances in major parts. They have stated that tolerances have not changed in many years, despite manfacturers going to thinner oils; that there was no correlation.
Dont worry about the lower number, thaqt is the winter spec. The lower that number is, the faster flow youll get when it is real cold. However, 5 vs. 10w- oils arent really an issue, as both are so thick compared to their viscosity at operating temperature, that either will give an adequate protection in most any climate.
GM puts in the 5w-30 oil now because it slightly increases fuel economy and reduces pollution at cold startup. They allow 10w-30 at temperatures over some level (I think 0F), which is smart, because if its that cold, then the 5 vs. 10w comes into play.
It probably also says that 5w-30 is preferred year round. Thats what Id use, unless it gets real hot, say over 100F all the time where you live. If so,then change to 10w-30 for those times.
JMH
JHZR2 - It probably also says that 5w-30 is preferred year round. Thats what Id use, unless it gets real hot, say over 100F all the time where you live. If so,then change to 10w-30 for those times.
Why would you switch from one 30w to another 30w?
Why would you switch from one 30w to another 30w?
Hey,
To my understanding, 30w oils are the preferred oils of most modern everyday vehicles. They give both an excellent balance of lubrication and gas mileage. If it was over 100* in my neck of the woods in the summer, I'd be using 10w30. From watching weather reports, Kansas in the summer can get pretty steamy so 10w30 would be my choice. 5w30 in the winter, spring and fall would be my choice, 10w30 for summer. However, Ohio doesn't see much 100* days moreso even 95* days. Hottest it gets here is about 90 or so. Most people use 30wt oils because they seem to be the most universal oils,,,,,AR
Ugly;
Here is the theory as far as I understand it...it may or may not have ever been true, now or in the past. And, especially with synthetics it is probably irrelevant for most conditions:
There is no difference between the behavior of 5w-30 or 10w-30 at operating temp (both '30's) - at first. The 10W-30 will theoretically be more resistant to breaking down due to it's smaller viscosity spread. That's all there is to it. People/manufacturers who recommend 10w-30 over 5w-30 for high temp/stress conditions have more confidence in the 10w-30's ability to hold up over time.
This is probably the reason why 10W-30 is recommended for some engines (ie the GM 3800 V6) while 5W-30 is specified for others (ie the GM 3400 V6) that can be found IN THE SAME MODEL CAR, like the Chevy Impala/Monte Carlo. You can use 5w-30 in the 3800 - below a certain temperature.
Like I said, I don't know if this is even really true anymore with today's high quality oils.
Okay so do you have an alternate explanation?
Why does Chrysler recommend switching from 5W-30 to 10W-30 when my car is traveling in >100F weather?
Why does Chrysler recommend switching from 5W-30 to 10W-30 when my car is traveling in >100F weather?
Because it's the "thickest" 30w you can buy. They won't put a 40wt in there since it won't garner the CAFE blessing.
Either 5w or 10w will be just fine. 10w is preferred in dino simply because it tends not to shear as quickly. But that's it.
Just use GC. All your problems will be solved.
Sorry I still don't understand
- why is 10W-30 "thicker"? I thought 5W-30=10W-30 at operating temps?
- why does 10W-30 not shear as easily?
I put "thicker" in quotes...it's the perception to the public. Yes you are absolutely correct, they're the same at operating temps.
Dino 10w-30 doesn't shear as easily due to the smaller spread in the two different numbers. The 5w has to spread 25 and the 10w has to spread only 20. Since dino oil starts out at the winter rating on the bottle and then gets processed to achieve the operating temp rating, there's less processing to make a 10w achieve 30 weight status compared to the 5w.
My manual says switch to 10W-30 over 100F. The reason is 10W-30 has fewer additives, more oil, and higher flash poiint. In other words, it protect better.
My statement was accurate. 10W-30 has a lower percentage of Viscosity Index Modifiers (additives) than 5W-30.
Sorry I still don't understand. What is the "less processing" that makes 10W-30 different from 5W-30? Is it fewer viscosity index modifierss?
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