Mix Oil Brands for Oil Change?

[Oil Changer]

Now read the link Shannow provided so you understand what it is you wrote.

Originally Posted By: ThirdeYe
Mix away, it'll be fine. API SN oils are compatible with one another.

 

[buck91]

Originally Posted By: sicko
Check out: http://www.pqiamerica.com/March2013PCMO/Marchsyntheticsallfinal.html

Looks like it'd mix really well with NAPA Synthetic or Valvoline SynPower. I'd say wait until NAPA has their synthetic on sale for $3.79 a quart (they have it every couple of months), and pick up a quart.


I noticed QSUD has much more calcium and much less magnesium than M1. What effect might this cause if you have a last quart of qsud and the rest m1 on a new oci?

 

[A_Harman]

Originally Posted By: BHopkins
Originally Posted By: sicko
Check out: http://www.pqiamerica.com/March2013PCMO/Marchsyntheticsallfinal.html

Looks like it'd mix really well with NAPA Synthetic or Valvoline SynPower. I'd say wait until NAPA has their synthetic on sale for $3.79 a quart (they have it every couple of months), and pick up a quart.


Thanks. That's pretty helpful. It looks like Valvoline Syn Power is also very similar in makeup to RP.


I think deven's head just exploded!

 

[wemay]

Originally Posted By: Oil Changer
Now read the link Shannow provided so you understand what it is you wrote.

Originally Posted By: ThirdeYe
Mix away, it'll be fine. API SN oils are compatible with one another.


Of the millions of people who have and continue to mix, how many do you think even care to research it after the product label gives them the OK? I don't mix but i know many who do and have been doing so for years. They don't have the time to read API papers and the like. Not that it's optimal but just not detrimental.

 

[subaru1991]

Is there any actual documented evidence that mixing certain brands can cause harm? What additives could potentially interact poorly?

 

[ISO55000]

Originally Posted By: subaru1991
Is there any actual documented evidence that mixing certain brands can cause harm? What additives could potentially interact poorly?


Absolutely there is.

I can also attest that in many failure analysis scenarios one of the root causes was an adverse reaction of lubricants.

It’s not the “brand” but the oil itself. Oil is basically 2 parts, the base oil and additive pack.

Base stock mixing isn’t that big of an issue in most cases but the additives are.
Depending on the type and concentration you can get an adverse reaction OR a cancellation of benefits.

Either one can severely damage the machine.

Regarding additives and interactions, one of the board lab guys would have to take you down that road ( those are the same people I go to because I’m not the chemist) but in industrial lubrication we take this VERY seriously and this is a major consideration even to the point of purge flushing when there is a lubricant changeover to a different package.

 

[doublebase]

I once mixed a couple of quarts of diesel oil, some generic 5w20 and 2 quarts of Super Tech 5w30 in my Accord. Now the diesel oil wasn't the norm, but almost every oil change I did this "blend", pretty much because of cost and availability. The thing now has 282k miles on it. This last summer I ran almost an exclusive light weight synthetic oil in it...it did burn some, but then again the car was not designed to tolerate a 0 weight oil.

 

[subaru1991]

[quote

Regarding additives and interactions, one of the board lab guys would have to take you down that road ( those are the same people I go to because I’m not the chemist) but in industrial lubrication we take this VERY seriously and this is a major consideration even to the point of purge flushing when there is a lubricant changeover to a different package.
[/quote]

Hopefully, someone can shed some light on what these possible negative interactions between automotive engine oil additives are so I can avoid them in the future.

 

[901Memphis]

Guys working at shops using quarts and jug containers will turn them upside after pouring the oil into a customers car and each container will continue to drain into a larger container and eventually be enough collected oil for your own vehicle and by the time you get enough together you have a multitude of different 5w20,5w30,10w30,15w40,10w40 mixed to make a heck of a brew. No issues running that, but these are the same guys doing 3,000 mile OCI too.

 

[Shannow]

subaru1991,
all over the counter engine oils are "miscible".

The test is to take a number of reference oils, mix them with the oil in question, then chill them to the point that they start to "not pour". The blend is then heated to 150C, then cooled to that cold point...then examined to see if there's any phase separation of solids drop out...that's it.

It doesn't test anything else, that your oil still meets sequence IVA, any of the cold temperature properties...nothing that the oil is actually certified against, except that it mixes with the reference oils.

The interactions that I've read are predominantly in the cold end performance...mixing 2 "0W" oils doesn't guarantee that you start the oil change interval with 0W in the sump.

There's a case where engine damage in taxis was observed when the replacement oil wasn't happy with the dregs of the factory fill, and wasn't pumpable even at quite high and reasonable ambient temperatures leading to damage...it's the cold weather performance that is likely to suffer. (*)

Unless you are playing with novel add packs (like Fuchs zinc free), you are unlikely to have any anti-wear additive interactions.

(*) should note also, that just because you start an OCI with a 0W, chances are it's not 0W at the end of the OCI either.

 

[camrydriver111]

What happens if I mix Mobil 1 and Castrol?

I know a lot of people say mixing is safe, but have you tried mixing those two specifically?

 

[Clevy]

Originally Posted By: camrydriver111
What happens if I mix Mobil 1 and Castrol?

I know a lot of people say mixing is safe, but have you tried mixing those two specifically?




I have. In fact I've mixed every known brand and grade at one point or another. Engines are spotless. No issues. Ever

 

[Clevy]

Originally Posted By: doublebase
I once mixed a couple of quarts of diesel oil, some generic 5w20 and 2 quarts of Super Tech 5w30 in my Accord. Now the diesel oil wasn't the norm, but almost every oil change I did this "blend", pretty much because of cost and availability. The thing now has 282k miles on it. This last summer I ran almost an exclusive light weight synthetic oil in it...it did burn some, but then again the car was not designed to tolerate a 0 weight oil.



Nonsense. Total,complete and utter nonsense. What's a 0 weight oil anyways. A 0w-20 is a 20 hot. So if there isn't any consumption with a 5w-20 there won't be with a 0w-20.
The 0 means the oil is thinner than a 5 or a 10 at start up. So to believe this in itself causes consumption,or the engine wasn't "designed" for it is nonsense

 

[Clevy]

All API certified oils are made to be compatible with one another no matter the brand. So mixing though may not be optimal certainly isn't going to cause harm.

 

[fdcg27]

This was my takeaway from your earlier posts in other threads concerning mixing different oils.
Ad pack compatability isn't the issue.
VII interactions are.
I have therefore concluded that while mixing different oils is never optimal, if one is intent upon running a blend, it would be better to use this blend during the warmer seasons.

 

[Shannow]

Clevy, they are made to be "mixable"...that's it...

 

[BHopkins]

Originally Posted By: wemay
OP, your initial inquiry didn't give me the impression you plan on making this a habit so i wouldn't worry one bit. And even if you were, most folks just read the bottle (where they say fully compatible) and move on.


You are right. It is just this one time. And since I've got an extra quart of PP on the shelf already, this seems like a good option, if there is no concerns with the mix. And from what some of our more experienced members are saying here, I think this is what I will do.

 

[BHopkins]

Originally Posted By: A_Harman
Originally Posted By: BHopkins
Originally Posted By: sicko
Check out: http://www.pqiamerica.com/March2013PCMO/Marchsyntheticsallfinal.html

Looks like it'd mix really well with NAPA Synthetic or Valvoline SynPower. I'd say wait until NAPA has their synthetic on sale for $3.79 a quart (they have it every couple of months), and pick up a quart.


Thanks. That's pretty helpful. It looks like Valvoline Syn Power is also very similar in makeup to RP.



I think deven's head just exploded!


Yea, I actually thought of him as I typed that. No offense intended, I was just expressing what I observed. However, your comment made me laugh out loud.

 

[BHopkins]

Originally Posted By: Clevy
Originally Posted By: camrydriver111
What happens if I mix Mobil 1 and Castrol?

I know a lot of people say mixing is safe, but have you tried mixing those two specifically?




I have. In fact I've mixed every known brand and grade at one point or another. Engines are spotless. No issues. Ever


Clevy,

Based upon your comment, I feel better about the idea of adding a quart of PP to top off the RP. Thanks.

 

[Clevy]

Originally Posted By: BHopkins
Originally Posted By: Clevy
Originally Posted By: camrydriver111
What happens if I mix Mobil 1 and Castrol?

I know a lot of people say mixing is safe, but have you tried mixing those two specifically?




I have. In fact I've mixed every known brand and grade at one point or another. Engines are spotless. No issues. Ever


Clevy,

Based upon your comment, I feel better about the idea of adding a quart of PP to top off the RP. Thanks.


No problem.

To be honest it's rare that I don't mix brands only because I'm usually finishing one jug and cracking a new one,so if I think back I don't remember the last time I didn't mix brands.
And every engine I own is spotless inside. When I first acquire a vehicle I carefully inspect under the valve cover if easy or I use my inspection camera and put it thru the fill hole to see. If any deposits are present I go a grade or 2 thicker than spec then add a solvent type oil additive and short intervals til I see bare metal. Then I use an ester based additive like liqui-moly motor oil saver as a preventative measure for gaskets and being an ester it finishes up the cleaning.
My methods may be unconventional at times however my results speak for themselves. All my vehicles run great til the body rots off and achieve extremely high miles,so I'm not doing any harm.