Mixed messaging from Mobil on mixing oils

[HawkeyeScott]

I emailed Mobil last month with a question about topping up a Mobil 1 oil change with Mobil conventional. They took awhile to respond. In the meantime, I went back to their website to see if I'd perhaps missed an answer in their FAQs. Sure enough, their site says it's okay, but does remind users that adding conventional to synthetic will diminish the effects of the synthetic.

From the Mobil site:

"Is it okay to mix conventional motor oil with Mobil 1™ motor oil?

Yes. Mobil 1 is fully compatible with conventional motor oils, semi-synthetic motor oils and other synthetic motor oils, should it be necessary to mix them. But the superior performance of Mobil 1 will be reduced by diluting it."

So, I was surprised when this email showed up a few days later from a Mobil email guy named Jim:

"Scott,

We can not advise mixing conventional oils with synthetics.

Thank you for choosing Mobil,
Jim.
Mobil Help Desk Team"

Naturally, I was very curious as to why Mobil would provide different answers to the same question. I followed up with Jim several days ago but haven't heard back yet. I'll share his response if I hear something. Needless to say, I'm confused.

 

[SwampSurvivor]

Mobil Help Desk Team is probably a marketing department who wants to sell you the more expensive synthetics

 

[SlipperyPete]

It can be done, but they don't recommend it. Like every other oil company. Is english really that hard?

 

[HawkeyeScott]

Saying yes it's cool but then saying it's not advised isn't a consistent answer.

 

[SlipperyPete]

Quote:
....should it be necessary to mix them.

We cannot advise mixing.......



It can be done, but is not recommended.

The world is a complicated place.

 

[OneEyeJack]

The oils are only guaranteed to be miscible, that is the result will be a homogeneous solution. There's nothing in that guarantee that promises that the resulting solution will meet any specification.

 

[Virtus_Probi]

Is Mobil going to discontinue their synth blend products?

 

[Joe90_guy]

I don't know how many oils I've blended in my time but I suspect it's in the tens of thousands. In all that time, I don't think I ever found two oils which were incompatible. On the off chance that something new comes out of R&D and is found to be incompatible, it almost never survives to full commercialisation.
Obviously if you make a 50:50 mix on synthetic and mineral, the oils performance will be somewhere between the two but nothing disastrous will ever happen.

 

[69GTX]

Perfectly clear.

Nothing will go wrong by mixing them assuming you now know that at best you have a synthetic blend in your engine and perform the next OCI accordingly. In the case of Mobil specifically, they have M1 20-30 grades and M5K with considerable sodium while some of their other oils have none (MSS and M1 0w-40). Whatever you end up with could be a blend no one has ever tested.

If Mobil recommended mixing their oils, then might as well say that they are wasting their time testing them in the first place.

 

[wemay]

Originally Posted By: Virtus_Probi
Is Mobil going to discontinue their synth blend products?


I don't believe they have one. The Mobil Super High Mileage claims to be a "blend" on the back of the bottles but their website says it's a conventional.



https://mobiloil.com/en/motor-oils/mobil-super/mobil-super-high-mileage

For long engine life
Mobil Super High Mileage premium conventional oils offer outstanding wear protection under a wide variety of operating conditions, and they have been proven to fight sludge and help reduce wear.

 

[SHOZ]

My next oil change the Accent is getting a blend of leftovers. 0w20, 5w20 and 5w30 of various M1 oils.

 

[demarpaint]

Originally Posted By: Virtus_Probi
Is Mobil going to discontinue their synth blend products?


Why?

 

[tig1]

Both answers are the same end result. Not that mixing causes damage. Mobil does not recommend mixing their M1 line with dino for the obvious reason. Nothing here new to report.

 

[Eddie]

Quite clear to me. Ed

 

[JMJNet]

The engine will know that you are mixing oil???

Those reply comes from Marketing as dictated by the lawyers.

 

[tig1]

Originally Posted By: JMJNet
The engine will know that you are mixing oil???

Those reply comes from Marketing as dictated by the lawyers.


How do you know that? Dino does reduce the value of the M1 synthetic line.

 

[A_Harman]

It's not the mixing of the conventional and synthetic base oils, it's the incompatible additive packages. (Says I who happily mixes 0w40 EF with 0w20 EP. It seems to work OK.)

 

[BlueOvalFitter]

If I have an M1 or PU OCI in my engine and it's low a qt. of oil I will add a qt. of conventional oil to the engine, if that's all I have. I don't see what the big deal would be. This is just my opinion. And, you know what they say about opinions............

On the other hand, I would NEVER let my engine oil level get that low!

 

[aquariuscsm]

Aren't all Mobil oils blends? M1 is a mix of mineral oil,pao,and ester (as shown by their mds) all mixing would do is water down one of the other,or both.

 

[Joe90_guy]

Originally Posted By: A_Harman
It's not the mixing of the conventional and synthetic base oils, it's the incompatible additive packages. (Says I who happily mixes 0w40 EF with 0w20 EP. It seems to work OK.)


All the common additives you will find in DI packs are oil soluble. Once they're in base stock, all additives are to all intents and purposes compatible.