Castrol's view on mixing oils

[Clevy]

Thanks for the link Shannow.
I appreciate the effort you put in helping me.

And those links the other day with the pyramids and so on cost me a nights sleep,but well worth the sacrifice.

Merry Christmas Shannow

 

[Shannow]

All good Clevy, Merry Christmas.

 

[aa1986]

Originally Posted By: Shannow
Anyway, the Standard only promises what it promises, which is why I'm swayed to not mixing anymore, and this idea if you need to have a top-up oil....SAE30 moewr oil. Plain zinc based additive, no VIIs, PPDs, or any of the other parts that MAY decide not to play nicely.


I'm thinking the same thing. But what to do with orphan quarts in different products and grades?

Make one Frankenbrew and run a shorter oci?

Note I don't have a big need for top up oil.

 

[wemay]

After reading the oil companies' statements as well as the studies shared by members like Shannow, I'd mix sparingly but doubt anyone who mixes often will have an issue. Clevy has pointed out various times, and rightfully so, how multiple frankenbrew UOA show no advanced oil degridation or wear.

 

[tig1]

Originally Posted By: surfstar
I'd reply saying that I will no longer be using Castrol, since other companies state that mixing is fine (along with the API itself).



No they don't. M1 says it's not the best because of different formulations. Much the same as Castrol.

 

[Shannow]

Counting up all my oil changes, the number that haven't been a Shannow custom brew (since reading Vizard on making your own syn blend) would be under 25%...Find Motul Ester on a huge special, and it was an "additive" on my next OCI, particularly the Nissan that takes a little over 7 litres.

Never have I had any issues, and living where -10C is about as far cold as it gets, I doubt I ever will.

Top-up is usually 700ml or so at 7,000km on the Nissan, and for the balance of the 10,000 OCI, I don't mind particularly what I've topped up with, but it's always been "good stuff", some synthetic that's in the shed.

Given that Castrol EDGE 5W30 A3/B4 is sometimes on special at less than dino prices, I'm leaning towards monogamy...but there's so much to get through, and so many shiney bottles out there.

 

[HTSS_TR]

Originally Posted By: wemay
Mobil1:

http://m.mobil1.com.sg/products/faq

Can different synthetic engine oils be mixed together?

Mobil 1 is fully compatible with conventional engine oils, semi-synthetic engine oils and other synthetic engine oils if you need to mix them. However, it is important to note that the superior performance of Mobil 1 will be reduced by diluting it in any way.

Originally Posted By: tig1
No they don't. Mobil 1 says it's not the best because of different formulations. Much the same as Castrol.

These two statements are not the same.
Mobil means to emphasize that their Mobil 1 is superior to all other oils. They didn't mean mixing Mobil 1 0W40 with Mobil 1 0W20 will reduced performance of either oil.

I changed brands/types in my LS400 almost every time I change oil in the last 21 years, the remaining old oil from 1 brand in the engine mixed with new oil from another brand and the engine is running great after 370k miles without any problem. It still has original valve cover gaskets without any leak.

I don't believe in the "Not Compatible", "Do Not Mix" advocates. According to the people who against mixing oil my LS400 engine should be rebuilt long long time ago.

 

[Shannow]

Originally Posted By: HTSS_TR
I don't believe in the "Not Compatible", "Do Not Mix" advocates. According to the people who against mixing oil my LS400 engine should be rebuilt long long time ago.


You obviously haven't read a word that they've said...

 

[aa1986]

Doug Hilary pointed out in another thread that the Japanese have historically sold a lot of vehicles in the 3rd world so design engines to run on whatever oils people find in places like Africa.

Nothing being said here is an absolute statement, it's just about weighing up getting the performance as designed by the experts by not mixing, vs getting less than maximum performance by mixing.

Who would want to mix 0w16 oils for example, seeing that they will contain more advanced additives to offset all the challenges posed by going thinner?

I posted somewhere else that Volvo now have an oil spec for a 0w20, which they put together with Castrol when designing two turbocharged 4 cylinder engines. Again, it might be more dangerous to mix that Volvo / Castrol 0w20 with another 0w20 than mixing modern 20 and 30 grade oils in a 20 year old LS400.

 

[tig1]

Originally Posted By: Shannow
Originally Posted By: HTSS_TR
I don't believe in the "Not Compatible", "Do Not Mix" advocates. According to the people who against mixing oil my LS400 engine should be rebuilt long long time ago.


You obviously haven't read a word that they've said...


+1

 

[KCJeep]

I used to be an avid mixer, it was just too much fun! These days I am getting away from it a bit more although I will dump about anything in the old cars for top off. Some here are reading too much into what was posted by Castrol IMO, they are not saying it'll sludge your engine up or you can't do it. They are saying you will not get optimum performance doing so the way I read it. Pretty much what Mobil says.

The more I learn about oil the more I realize my tinkering with it is less likely to be a positive. I do use MoS2 in the Jeep, but that simply uses the oil as a carrier.

I did an intentional blend all with Castrol High Mileage quite a while back, and did a used oil analysis. I did not end up with the viscosity I expected despite the Widman calculator, and I had been running nothing but Castrol High Mileage prior to that as well so it wasn't contamination from a different oil either.

Just something to think about.

 

[Shannow]

KCJeep... This the one ?

 

[aquariuscsm]

I'm guessing Castrol's response is just a "disclaimer" per se "just in case" adverse effects were to happen if someone did a crazy oil mix.

 

[SilverC6]

Certainly an engine isn't going to blow up if you mix oils.

But mixing different grades and brands can't be ideal.

Why pay for a high performance oil and adulterate it with a couple of quarts of this or that?

You're kidding yourself if you think you are creating some kind of magic elixir the oil companies haven't invented yet.

 

[HKPolice]

Originally Posted By: Shannow
KCJeep... This the one ?


Wow this is surprising considering the low mileage. The mix was with different grades of the same type of oil, imagine how bad it could be with different grades from different brands that use different types of additives like Mg vs Ca and Moly vs Sodium.

I think a lot of people are trusting the API standard for mix compatibility too much. I don't think the standard states that every oil must be tested in a mix with every other oil to make sure they work. I actually doubt they're tested against other retail oils at all, most likely just a standardized oil formula and as long as it stays in grade it's considered a pass. I doubt any endurance tests are done on mixed oils.

Sure, when you change oil there will be some residual from the previous change but no where near as much as 2-3 quarts worth.

If anyone has a link to the API standard for mix compatibility please post it, I'm too lazy to dig for it.

 

[teddyboy]

Originally Posted By: gfh77665
There are roughly 3.417 Gazillion anecdotal experiences around the globe that prove otherwise.



And that's the conservative estimate for the number.

 

[ledslinger]

Their warning is mostly about staying within grade when adding, the exact compatibility feature I'm least worried about is viscosity. Maybe because I have the least understanding of it, chemistry compatibility is of more concern. Mostly chemical reaction of additives, not base oils. I assume all base oils mix well. I don't know if additives might combine or react to another compound, or if different additive compounds can do their thing along side of other types of additives formulated with a different chemical philosophy.

Running GC and Shell Helix mix in my Concorde now, gremlins are likely growing from this primordial ooze at this minute.

 

[ltslimjim]

Originally Posted By: Shannow
KCJeep... This the one ?


We could argue this other one. also showed better results afterward perhaps due to simply being the correct viscosity for the engine instead of basically a sheared out of grade 30w oil when he blended.

I wager if he got the viscosity right we have a good chance of seeing similar numbers more in line with the Pennzoil conventional run, similar mileage but barely less overall metals. A smudge of aluminum and 10-15 ppm of iron is not huge in of itself.

 

[Shannow]

Originally Posted By: HKPolice
If anyone has a link to the API standard for mix compatibility please post it, I'm too lazy to dig for it.

Posted it here...

You are correct, the oils have to be mixed with each of 6 ASMT reference oils, cooled to find the new pour point (not a standard, just what the new blend pours at), heated, then cooled to the discovered pour point and thawed.

The lube is checked for precipitates gelling, and splitting...that's it...no other tests, just a salad dressing test. Doesn't check that it's still SN, whether it's still 0W...nothing except it doesn't display an adverse chemical reaction.

 

[wemay]

I'm not a chemist but my layman's common sense would 'suggest' that mixing two SN, 5w20 oils would yield the same. The additves of each being diluted if using different packages of course. As for mixing different viscosities, I wouldn't now, but I would assume a viscosity somewhere in the middle?