Two Mazdas One Oil??

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Hello All,
I'm a new member to this site although I have been coming here from time to time and find it very interesting. I've picked up a lot of great information here thanks to all you great members.

So, here is what my OCD brain has been dwelling on concering my two Mazdas:

Car #1 is 2010 Mazda6 with 2.5L built in Michigan.
Mazda specifies 5w20 oil. 37,000 on counter. First 34,000 used Motorcraft 5w20 Synthetic Blend Oil. Recently changed over to Mobil 1 5w20 due to great deal on 7 gallons purchased at AAP ($2.50 / quart)

Car #2 is 2011 Mazda3 with 2.5L built in Japan.
Mazda specifies 0w20 oil. 4,100 miles on counter. Did first oil change at 1,700 using Mobil 1 0w20 oil.

I'm pretty sure that Mazda changed specs simply for CAFE reasons and that the two engines are mostly identical. I'm really thinking about running 5w20 in both simply because I want to lean more toward engine protection vs. fuel economy. Both cars average right at 27.5 to 28 mpg with mixed city/hwy driving.

Is there really a dimes worth of difference in these two Mobil 1 oils that it would matter either way?

0w20
vis 40 - 44.8
vis 100 - 8.7
index - 173
hths - 2.70

5w20
vis 40 - 49.8
vis 100 - 8.9
index - 160
hths - 2.75
 
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You say that you think Mazda changed the specs for CAFE reasons. Is there any reason you think this? Both oils should offer comparable specs at operating temperatures (and per your information posted, they do).

Use either with confidence - the 0w20 will likely offer marginally improved start-up wear protection, both will offer similar protection at operating temperature.
 
I based it on the fact that it's the same engine. Another possiblity is that they speced it to 0w20 just to push people toward sythetic oil since there is no conventional 0w20.
 
You can use Mobil 1 0W20 in both cars, if that is your question...that's what I would do...I know, I know, look at my sig and it looks like I can't make up my mind, but that's b/c there is a bunch of oil in the stash that I got on sale...
 
How much of a protection difference would you think there would be during cold starts between the 44.8 and the 49.8?

Conversely what about operating temp. protection difference between 8.7 and 8.9?
 
Originally Posted By: Mark_Walk
How much of a protection difference would you think there would be during cold starts between the 44.8 and the 49.8?

Conversely what about operating temp. protection difference between 8.7 and 8.9?


Likely very little on both accounts. However, you live in Kentucky and your "cold starts" in the winter may not be 40 deg C. At temperatures lower than that, the advantage of 0w20 becomes greater.
 
Originally Posted By: Mark_Walk
How much of a protection difference would you think there would be during cold starts between the 44.8 and the 49.8?
Conversely what about operating temp. protection difference between 8.7 and 8.9?

First, as you mentioned in your first post, Mobil 1 0W-20 is heavier than most OTC 20wt oils. It is heavier than all 5W-20 conventional oils and that is all that is required for both engines mentioned.

Secondly, you're comparing the wrong viscosity values.
You should be comparing HTHS vis and the Viscosity Index of both oils and this is a good habit to get into when comparing any oils.
Mobil 1 0W-20 is somewhat lighter with it's HTHS vis of 2.7cP and it will be lighter at all start-up temp's due to it's significantly higher VI of 173; the lower the start-up temp' the greater the viscosity difference between the two oils.
Consiquently for your application Mobil 1 0W-20 is the preferred choice.
 
Very good point on the Mobil 1 0w20 being heavier than 5w20 conventional oils.

Do you think Mobil acheived the higher VI of 173 by going to a more agressive additive package or is it due to starting with a better base oil package over the 5w20?
 
Originally Posted By: Mark_Walk

Do you think Mobil acheived the higher VI of 173 by going to a more agressive additive package or is it due to starting with a better base oil package over the 5w20?

Very good question, and that is one of the advantages of 0W-XX oil is that they must use naturally higher VI base oils to acheive the extreme cold performance targets that 5W-XX don't need to.
 
Originally Posted By: Mark_Walk
I know the Fusion and the 6 are built on the same platform....maybe at the same plant in Michigan.


The Fusion is built on the previous-generation Mazda 6 platform in Hermosillo Mexico.
 
Originally Posted By: sjw91
Originally Posted By: Mark_Walk
I know the Fusion and the 6 are built on the same platform....maybe at the same plant in Michigan.


The Fusion is built on the previous-generation Mazda 6 platform in Hermosillo Mexico.


I really like the 2.5 engine. I think the block is the same as the Ford with a different head. I've heard Mazdas are tuned to run a little richer than the Fords.
 
I've used both oil weights for years in my Mazda6s with no problems. I'm currently running Mobil 1 Extended Performance 5w20 for an extended OCI.
 
Originally Posted By: EricZoom
I've used both oil weights for years in my Mazda6s with no problems. I'm currently running Mobil 1 Extended Performance 5w20 for an extended OCI.


The EP was on sale with 5qts and filter at AAP for $33 I believe....just $2 more than regular M1.
 
I'm using Mobil 1 0w20 in my Mazda and I follow the max 7,500 mile OCI specified in the owner's manual. Mobil 1 is pretty much the only 0w20 I can find fairly regularly.
 
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