Any issues with this blend?

[99Saturn]

I have some Castrol Edge 5w50 and Mobil 1 Extended Performance 0w20 that I was planning on mixing (2 qts. Castrol, 3 qts. M1) for a couple of oil changes in our Cobalt (2.2L ecotec with 117K).

Just curious:
1. any issues with the add packs here?
2. any recommendations on how long to run the oil change?

TIA.

 

[A_Harman]

This is a strange mix. They are both long-drain oils with Magnesium-rich detergency. Mixing a 50 and a 20 should give a heavy 30, which would be fine. But the 5w50 Castrol will probably shear terribly in the Ecotec, so maybe you'll end up with a light 30. From the standpoint of TBN, you could probably go 15k miles between oil changes, and two changes would be 30k miles, which is more than I would feel comfortable running a mongrel blend.

I think run the first OCI for 8000 miles, and used oil analysis to see how it held up, then run the 2nd OCI longer if the results were good.

 

[Shannow]

I don't know that you should anticipate on two such disparate oils following the rules of thumb...one is very high in VII, and other probably nearly none...

My last "scientific" brew in my Nissan used two oils that I bought on closeout, for 1/3 of the RRP, but at 5L respectively not enough to fill my Nissan...Target was HTHS about 3.6

Penrite Race 5W30 (4L)
Mobil 1 5W50 (3L)

leaving about half a litre for "adjustment"

Subsequently found that the Penrite stuff was HTHS of 3.4, which put me way over the target, so I added about 700ml of 5W20.

Engine normally takes a litre at 7,500km, this time it was 5,000km, and lacking any of the ingredients, used Caltex C3 from the stash...ran it a couple of days and chickened out and dumped it.

Have a sample in my (for the record, not calibrated, -20C) freezer at the moment, and it's not playing like a 5W by any stretch, not quite as bad as an SAE30 but nothing like the 5W50 in sloshability.

Just an anecdotal warning.

 

[gfh77665]

Two excellent oils, guaranteed to be fully compatible. Mix away and don't even think about it for 10K.

 

[Shannow]

Originally Posted By: gfh77665
Two excellent oils, guaranteed to be fully compatible. Mix away and don't even think about it for 10K.


No, guaranteed to be "miscible"...that's all.

 

[gfh77665]

Originally Posted By: Shannow
Originally Posted By: gfh77665
Two excellent oils, guaranteed to be fully compatible. Mix away and don't even think about it for 10K.


No, guaranteed to be "miscible"...that's all.


All major oils are fully compatible.

 

[Quattro Pete]

Originally Posted By: gfh77665
All major oils are fully compatible.

Define "compatible."

Nobody guarantees that 2 + 2 = 4 in this case.

 

[gfh77665]

I don't have to "define" anything. Look at the FAQ's on any of the majors websites.

BTW, major brands have been mixed with abandon 73.145 gazillion times with zero problems.

I am not going to senselessly debate SEMANTICS here. Mixing these two oils is perfectly FINE.

 

[Quattro Pete]

Look at some of the articles Shannow posted on the subject.

Yes, in general you will have zero problems, but what you may end up with is a combination that is lesser than the sum of its parts.

 

[OVERKILL]

Originally Posted By: gfh77665
Originally Posted By: Shannow
Originally Posted By: gfh77665
Two excellent oils, guaranteed to be fully compatible. Mix away and don't even think about it for 10K.


No, guaranteed to be "miscible"...that's all.


All major oils are fully compatible.

Yes, which is a far cry from optimal, which, conveniently, is what a fully formulated lubricant is designed to be.

I can mix coolants too, they are "compatible" but you know that the lifespan of the mixed product is reduced because of the blend. The same (and more) goes for oils. Compatible doesn't mean that it is advantageous, beneficial or even WISE, it just means that the fecal matter won't go sideways if you do it. That's all it means. That is the definition of compatible in this context.

 

[Dallas69]

There's two sides to this and no one is going to move.
People need to do whatever makes them happy and go their own way.
One wont convince the other.

 

[Shannow]

Originally Posted By: gfh77665
I don't have to "define" anything. Look at the FAQ's on any of the majors websites.

BTW, major brands have been mixed with abandon 73.145 gazillion times with zero problems.

I am not going to senselessly debate SEMANTICS here. Mixing these two oils is perfectly FINE.


I'm only offering what the API and their standards offer...they are mixable with 6 reference oils, cooled to thei combined gel point, heated to 150C, recooled to the previous cold temperature, and doesn't split like salad dressing...that's ALL the API offers regarding mixing.

People who claim that mixing two 0W20 SN oils from different companies, and the resultant will "of course" be a 0W20 SN are making facts up...the API doesn't guarantee that...just that they will mix, and stay mixed, and therefore the most catastrophic type of incompatibility is avoided.

As to "all" the oil companies

http://www.lubricants.total.com/contact-et-faq/faq.html
Quote:
Lubricants are always optimized to meet the requirements of international classifications (API, ACEA). However, there are many ways of formulating a specific type of lubricant. Mixing two oils that have equivalent properties will not pose a problem, but final performance cannot be guaranteed. All market oils (petrol engine or diesel, mineral or synthetic) are mixable. However, a blending of two oil qualities lower the superior quality.


The OP, 99.999% won't have a failure using the brew, but given the disparity between the basestocks, and amount of VI in each, can't even be reasonably confident in the KV100, HTHS, or that it's still a 5W.

 

[Dallas69]

At the end of the day mixed oil is just that,mixed oil.
I think todays oils are of such high quality that even if the final result is less than optimal,it is still more than good enough for most engines,especially with hot weather on the way.
For example,any mixed brew in my 1987 truck is still way better than what was in it from the factory.
I never go as crazy as to mix 4-5 different brands at once.
I use up strays for topping and one qt of orphan to go with a 5 qt ju.
Never had issues and whenever I did any valve cover gasket replacement the insides were always clean.
This is my position on this.

 

[gfh77665]

Major brands have been mixed with abandon 73.145 gazillion times with ZERO problems.

 

[Quattro Pete]

Nobody is arguing that point with you.

Some of us just wanted to point out the downsides.

 

[MrQuackers]

The only way to be assured of full compliance with standards is to use the same product every time and at each OCI dump the oil, fill and idle for 10 minutes. Then dump and fill again. I guess.

 

[GenesisGuy70]

I'm sorry but I really do not understand why people do this. I know some people love their "frankenbrews" but I just think it's silly. Just put in the spec'd oil weight and grade and be done with it.

I'll never understand it....

 

[Dallas69]

It's very simple.
If you have a 6qt engine like me,I use a 5 qt jug and another qt of something if I don't have the same brand handy.
I have a big stash of oil and I use what I have.
Not hard to understand.

 

[Quattro Pete]

Originally Posted By: Dallas69
I have a big stash of oil and I use what I have.
Not hard to understand.

You have a big stash of oil, but not big enough to have a sufficient amount of the same oil type for a single oil change?

Doesn't that kind of defeat the whole point of an oil stash?

 

[Dallas69]

Sure I have plenty of single qts to make a change using yhe same brand.
It is when I use a jug that I dont always have a single that matches.
I got a few jugs of Castrol for 5 bucks during AZ sale but no singles.Same with ProLine and Ultra,many jugs but only singles of Valvoline,Smittys,M1.
It's pick and choose when I change oil.
No biggy.
I only buy oil when it is at a deep discount,never pay more than a buck a qt either by jug or single.