additive clash question

JHZR2

Staff member
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New Jersey
Hi, I am curious about what additive clash really is. Seems like an odd concept. -will the surfactants clump up into micellar structures if there are different types? -There can't be many forms of the additives which are miscible in oil, and even if they are why would they clash? -What is the reaction mechanism of this 'clash'? -If we have a certain molecular structure, i.e. a negatively charged group that makes a Calcium detergent additive neutral overall... And that group is less reactive than another which is attached onto say boron... The groups could switch, its all reactivity and electronegativity... but that isnt going to change the fact that the calcium and boron are in the oil for detergency reasons... So what is the problem? Is additive clash really an issue before you get to the very last trace amounts of free detergent additives? Is additive clash something that is only improtant in engine oils? SInce ATF and rear end lubes dont have as many things to combat and keep clean, due to the nature of their service, does one have to worry about mixing them? Thanks for the help JMH
 
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St. Charles County, Missouri
I believe that additive clash is over stated as a problem. A few manufacturers like Lubrizol make most of the additives. An analogy might be trying to make a cake mixing one box of Duncan Hines and one box of Betty Crocker cake mix. Given similar flavors, the resulting mix might not be as good as the original recipe, but it probably would still be cake.
 

Patman

Staff member
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Oakville, Ontario
quote:
Originally posted by Steve S: All motor oils are mixable . I don't know who made the term up it is an outrite lie.
It's not really a lie. Sure, you can mix oils and your engine will not seize up. But when two different additive packages are present such as when you switch oils for the first time, and you try to go directly to extended intervals, that first change can often result in the TBN dropping faster and the oil oxidizing faster too.
 
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Duvall WA - Pacific NW USA
I have seen the rapid TBN drop!! "additive clash" is a eye popping term...probably overstated, over used....the words themselves are connotative of something not good in the ol' engine. BUTT it does happen. Best quick (VERY OVERSIMPLIFIED) example is switching from one type of oil that has some AW additive that can form acidic type compounds (this oil is formulated to deal with these compounds - nothing wrong with this btw) - to an oil that doesn't form exactly the same or less acidic compounds therefore has a different basic stabilizer - voilà TBN takes a quick nose dive. As Patman says - NO extended OCI when switching!!! I, as an Amsoil dealer have been preaching this for years!!!! [Big Grin]
 
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Ocala, Florida
In some cases other than just TBN drop, some engines will develope oil usage due to this as I've seen as well. This will normally continue but deminish over a couple of oil changes. Again, due to additive clash. This is more prevelant in gas engines than diesels as well. This is one reason why I suggest a purge with neutra 131 prior to change over but most time you won't have a problem as you point out. But when you do, you can and should do a purge then try again, many just change back to the old oil and continue with a bad taste in their mouth about the other one that seem'd not to work due to the clash.
 
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PHX
[QUOTE] But when two different additive packages are present such as when you switch oils for the first time, and you try to go directly to extended intervals, that first change can often result in the TBN dropping faster and the oil oxidizing faster too. [QUOTE] Do we have any idea what these different additive packages are and why/how they "clash?" I'm hearing alot of general talk...but no specifics....... [I dont know]
 
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Ocala, Florida
There's no real way of telling if you are experiencing additive clash. Normally during a change over, you'd run your first oil drain at normal drain intervals with analysis, then after that drain, with the use of anlaysis, then you'd start looking to extend your drains. It is suggested to never try and extend on the first oil change as it has to over come the last oils additives, to what levels, it is impossible to say with out doing analysis.
 

CJH

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Location
Pennsylvania
Shouldn't this be on the additive thread? [Off Topic!] I asked a question about when to take a sample for used oil analysis and it was considered off topic in the used oil analysis thread and moved. I dont get it!
 
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Guys maybe so but over the years I have seen many fleets change oils as they change management and their equipmemt lasts as long as those sticking to one brand. In real life what is the difference in engine life. Long oil drains may be fun I have done it but I am not totally sold on getting the last miles out of the oil, running on dirty oil is not good. Waiting for an analysis to tell when to change the oil, is running dirty oil. to many variables .For example over the road trucks have a predictable useage ,cars don,t. When doing an extended drain oil analysis is performed at scheduled interals to keep track of the results .Using amsoil for example , I wouldn't say the oil would last 1 year or x miles unless proven by scheduled analysis. [ May 09, 2003, 01:15 AM: Message edited by: Steve S ]
 
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I will put my foot in my typing mouth, why not use amsoil all year because it will protect your engine better than 5w/30 petro oil. This way the full benefits of the amsoil will be realized.
 
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Location
Washington St.
quote:
Originally posted by CJH: Shouldn't this be on the additive thread? ....
This topic is referring to the additive package that's present in any and all finished motor oil products, not a single add-in product you can put into the oil. Ken
 
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Location
Bolivia
While agreeing with Bob that you should not jump to extended intervals with the first brand oil change, I know that many blenders change their formulations several times a year depending on additive costs and spot markets. They do not tell you the old or new formulation. For some brands I have so many different formulations that I couldn't tell you what their intended formula is. But their is additive clash, mainly from mixing acidic and alcaline products (Chevron's Clarity Hydraulic Fluid is not compatable with normal Hydraulic Fluids) Additives will precipitate in the presence of moisture. Gear oils are acidic while motor oils are alkaline. I know some people who mix them thinking they are doing good. Many air compressors recommend either Dexron or Turbine oil. Dexron is Alkaline and Turbines oils are acidic. When changing from one to another you should flush.
 

Jay

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Idaho Falls, ID
The Shell tech expert had this to say about additive clash:
quote:
Regarding oil compatibility, if you mean topping off with something other than the crankcase fill, there are rarely compatibility issues. If you mean blending oils with different base stocks or different brands, that does present compatibility issues – whether the oils is synthetic or not. Today’s multigrade oils contain over a dozen separate additives, carefully chosen for, and carefully blended with, specific base oils. The formulation must be balanced, as some additives can interfere with performance of other additives. These formulations have been demonstrated to have specific performance characteristics. Putting together two separate oils makes a third oil with unknown performance. There may or may not be compromised performance.
 
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43,650
Location
'Stralia
quote:
Originally posted by Jay: The Shell tech expert had this to say about additive clash:
quote:
Regarding oil compatibility, if you mean topping off with something other than the crankcase fill, there are rarely compatibility issues. If you mean blending oils with different base stocks or different brands, that does present compatibility issues – whether the oils is synthetic or not. Today’s multigrade oils contain over a dozen separate additives, carefully chosen for, and carefully blended with, specific base oils. The formulation must be balanced, as some additives can interfere with performance of other additives. These formulations have been demonstrated to have specific performance characteristics. Putting together two separate oils makes a third oil with unknown performance. There may or may not be compromised performance.

Jay, that sounds like a half brained answer from the tech in question. 4 litres of Brand A and a litre of Brand B makes an unknown quantity Brand C if done intentionally. However, 4 litres of Brand A topped up with a litre of Brand B is OK. Even if topped up with another litre of Brand D later in the change interval ? When I was working at a Shell service station years ago, the only fluid that we were cautioned about mixing was brake fluid.
 
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