Mixing Mobil 1 0w40 with GC 0w30

[fredf]

I have 4 litres of Mobil and 1 litre of GC that I would like to mix together (VW GTI) for my next oil change.

Is it ok to do this or will add packs not play well together?
I know this has been asked several years ago but I thought I saw more concern recently about the non oil components perhaps not playing well together.

Sorry for the question.

 

[wemay]

Not the same oils but same premise...

https://bobistheoilguy.com/forums/ubbthreads.php/topics/3907168/&quot

 

[buster]

You can, but I wouldn't. For one change it's fine but mixing is not really a good thing to do over time.

 

[fredf]

Originally Posted By: wemay
Not the same oils but same premise...

https://bobistheoilguy.com/forums/ubbthreads.php/topics/3907168/&quot


I read that thread before posting here. Some people think it's ok within the same company but perhaps not between companies like Mobil and Castrol.

I change my oil once yearly (only driving about 8k km annually). I have a 4 litre jug of Mobil 1 and have a litre container of GC. So I was hoping to use them up together.
They will sit in the engine for a year, though.

 

[Quattro Pete]

You'll be fine, but don't make it a habit.

 

[fredf]

That's what I though but I'm intrigued by the comment 'don't make it a habit'. If it's ok for a year why not for longer--I mean a second time.

 

[Quattro Pete]

Because of what's been discussed in all the other threads - additive clash, impact on cold flow properties, etc. Even doing it one time isn't ideal, but if that's the only way for you to use up leftover oil, then it is what it is. Your engine is not going to explode.

 

[BrocLuno]

Go ahead and do it. It's no different than if you were on a trip and down a qt/liter, likely the top-up oil would not be the same brand or formula...

98%'ish of oil is just that (oil, including VII's) and if they are both rated the same like SN, the add packs will not be too far off.

A full sump is better than some minor add pack obsession since oil is cooling fluid as well as a lubricant. Full is more useful than low...

These are both good oils and they should not fight. If there was some sort crazy reaction between these two, it would have come out a long time ago. I'm sure many, many vehicles have been topped up with one or the other mixing along the way...

 

[A_Harman]

It's not like the GC/Mobil 1EF mix is going to make your bearings fizz like an Alka-Seltzer. On BITOG we normally say it's OK to do a cross-brand mix occasionally, but don't do it all the time.

Another strategy you could consider is do 100% fill with Mobil 1 0w40, and use the GC for topoff during the OCI.

 

[CT8]

It won't hurt a thing. Motor oils are compatible.

 

[fredf]

Thanks all!

 

[OneEyeJack]

Compatible? More correctly, miscible. There's absolutely noting positive to gain and there could be an additive clash. Why risk a problem for a few bucks. Those posting here that it's okay could be wrong. There's no way to know, for sure. Just because nothing happens immediately that you notice does not mean that all is well.

One example of a problem mixing oils.

 

[Shannow]

Originally Posted By: CT8
It won't hurt a thing. Motor oils are compatible.


miscible you mean...

The standard requires that the test oil is mixed with a number of reference oils (not every oil), gets heated to 230C, cooled to the pour point, and doesn't split like salad dressing.

That's all the standard promises.

 

[CT8]

Myth: You can't mix brands of motor oil. Fact: Mixing brands is not the best practice because the additive systems in each may be different and when mixed may not function as efficiently as desired. However, no serious problems will occur if you must add a different brand of equivalent quality between oil changes.
CITGO.com, Consumer Products, Oils, Engine Oil Myths
https://www.citgo.com/ConsumerProducts/Oils/EngineOilMyths.jspCitgo

 

[CT8]

Provides excellent engine cleanliness through superior sludge and varnish protection
Helps reduce engine wear at high temperatures with improved viscosity stability
Provides outstanding high-temperature protection under severe driving conditions
Provides superior cold-temperature protection through faster oil flow at start-up
Formulated with antiwear additives that stay in your oil longer for outstanding protection against friction and wear
Helps maintain fuel efficiency for the life of the oil*
Is fully compatible with all conventional and leading synthetic motor oils
- See more at: http://www.valvoline.com/our-products/motor-oil/syn-power-full-synthetic#sthash.LfKzoaNc.dpuf

 

[CT8]

COMPATIBILITY
AMSOIL OE Synthetic Motor Oil is compatible with conventional and other synthetic motor oils. Mixing AMSOIL OE Synthetic Motor Oil with other oils, however, will shorten the oil life expectancy and reduce the performance benefits. Aftermarket oil additives are not recommended for use with AMSOIL OE Synthetic Motor Oil.

 

[CT8]

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

 

[CT8]

ABOUT RED LINE MOTOR OIL
Fully-synthetic ester formula for passenger cars, light trucks, performance vehicles and marine applications
Excellent wear protection and friction reduction across a wide range of operating conditions
High detergency allows extended drain intervals and provides increased cleanliness
Improved fuel economy and ring seal for more power
Superior high temperature stability and oxidation resistance increases lubrication of hot metal compared to other synthetics
High natural viscosity index (VI) provides thicker oil film in bearings and cams
Less evaporation than other synthetics for improved efficiency and ring seal
All products are completely compatible with other conventional and synthetic motor oils

 

[Shannow]

Here's the actual ASTM D6922, the standard to which they are tested, and the actual words.

https://bobistheoilguy.com/forums/ubbthreads.php/topics/3503628/Re:_The_oft_quoted_ASTM_D6922

Read them for yourself, and see what the actual test is and promises.

 

[Shannow]

And here's what SOPUS say, at the very top of this page....

Quote:
The physical results may be very much as you expect i.e. viscosity is likely to be predictable following well known physical laws however the chemical effects are highly unpredictable. Wear performance is not dictated solely by the amount of wear protecting additives in an oil, the efficacy (effectiveness) of the additives must also be considered. Efficacy can be negatively impacted by changing the balance of a formulation package. The approach you suggest could conceivably result in poorer performance, I would recommend choosing a single tier of product, and Pennzoil Platinum has been designed to offer complete protection including unsurpassed wear performance.