Ok to mix oil brands?

Can I pour half Mazda moly and half castrol synthetic 0w-20 into the engine? Is it all the same thing at the end? What about pouring Mazda moly and then adding in castrol to top off when oil gets low? Manual says you can use castrol brand.
 

ColoradoDriver

Gen-1 Kodo Design
Contributor
:
Denver, CO
:
2014 CX-5 Touring
Agreed. As long as they are the same grade, go ahead.

I would not however mix say a 0w20 with a 5w30.
 
:
2013 Mazda CX-5 Sport FWD Auto
The only issue with mixing brands of motor oil is the change interval. If one oil is something like Mobil Annual Protection, they advise not to do an extended interval if mixed with a different brand. Stick with a normal change interval. Other than that, youre good to go!
 
:
'16.5 CX-5 Touring AWD
I believe he is saying as long as they have the same certifications, ratings, etc.

With regards to API starburst, yes.

Sorry @erhayes, I chose poor wording in my original post.

It's not there's a physical test, but more so in order for an oil to achieve the API starburst, it must be miscible with other API certified lubricants. The basic chemistry between various lubes is very similar between Company A and Company B, while the additives and base group(s) may differ, the physical chemistry of each completed product is similar due to the miscibility factor that the API imposes.

You can (and many do) also mix various weights. For instance, I have 3 gallons of 10w30 sitting on the shelf. In the summer, when I run through my 5w30 stash I will be using two quarts of 10w30 and three quarts of 0w20. This should result in a viscosity that is comparable to a thin Xw30 or thick Xw20 depending on the specific cSt values of each oil.
 
Last edited:
:
'16.5 CX-5 Touring AWD
With regards to API starburst, yes.

Sorry @erhayes, I chose poor wording in my original post.

It's not there's a physical test, but more so in order for an oil to achieve the API starburst, it must be miscible with other API certified lubricants. The basic chemistry between various lubes is very similar between Company A and Company B, while the additives and base group(s) may differ, the physical chemistry of each completed product is similar due to the miscibility factor that the API imposes.

You can (and many do) also mix various weights. For instance, I have 3 gallons of 10w30 sitting on the shelf. In the summer, when I run through my 5w30 stash I will be using two quarts of 10w30 and three quarts of 0w20. This should result in a viscosity that is comparable to a thin Xw30 or thick Xw20 depending on the specific cSt values of each oil.

Gonna quote myself here because I was wrong. There IS a specific test that is run to ensure miscibility. If you're interested in researching, go ahead and look into ASTM D6922.
 
:
13' CX-5 and 16' Mazda6 both Touring w/Tech/Bose
As a supporter for Oil-Brand fanboyism......I approve the mixing of oils!!!
 

erhayes

Contributor
:
2021CX5 Reserve
So to be absolutely sure that mixing is OK we must ascertain whether the two oil meet the ASTM D6922. Haha. Ed
 
:
'16.5 CX-5 Touring AWD
So to be absolutely sure that mixing is OK we must ascertain whether the two oil meet the ASTM D6922. Haha. Ed

No, not at all lol.

ASTM D6922 is the test that the API requires in order to receive API approval. So ALL API approved oils have undergone the testing.