Add packs on same brands, different weights

[HawkeyeScott]

I just read an interesting thread from awhile back about additive packs and their variance from one brand of oil to another. But within brands and specific varieties of oil - say Pennzoil conventional - do the add packs vary by weight? I understand some don't think it's a good idea to mix, for instance, 3 qts. Valvoline and 2 qts. Quaker State because they likely use at least somewhat different add packs and that agents in those add packs could adversely affect one another. But what's the prevailing thought on mixing weights of the same oil?

 

[Steve S]

The agents in the add pack are similar if not the same ingredients. Look at the posted UOAS that are posted.

 

[FrankN4]

I know that Mobil 1 uses a different add pack in their 15W-50 than they use in their 5w30. The 15W-50 has more moly, boron, and a lot more ZDDP(1200 ppm) Valvoline has a very similar add pack in their 5w30 and 20W-50, but, according to Valvoline tech services, they use very different base oil chemistry and friction modifiers.

When blending oils you are either strengthening one oil, weakening another, or both. I know that sounds ridicilious/obvious. I considered blending a 20W-50 synthetic with the same company/line 10W-30 synthetic to get a usable 30 grade with a HTHS of at least 3.5 and a 100C cSt of at least 76. I called the company and they said "don't do it." Their answer also said that although the add pack was almost identical, the chemistry of the oil was different and the base oils were different. All that told me was that there was enough that I didn't know to keep me from chancing it.

 

[glenncof]

Originally Posted By: FrankN4
Valvoline has a very similar add pack in their 5w30 and 20W-50, but, according to Valvoline tech services, they use very different base oil chemistry and friction modifiers.

When blending oils you are either strengthening one oil, weakening another, or both. I know that sounds ridicilious/obvious. I considered blending a 20W-50 synthetic with the same company/line 10W-30 synthetic to get a usable 30 grade with a HTHS of at least 3.5 and a 100C cSt of at least 76. I called the company and they said "don't do it." Their answer also said that although the add pack was almost identical, the chemistry of the oil was different and the base oils were different. All that told me was that there was enough that I didn't know to keep me from chancing it.


Yea, the 20W50 is PAO per MSDS and the rest of the Synpower line is a GrpIII as I understand.

 

[jldcol]

Additives generally are there to prop up the deficencies of the base oil. If the base oil varies, then should to the add packs. Certain groups are better cleaners for example and will perhaps use less cleaning adds. I think lube oils are made in batches, so a given batch base oil may have a,b,and c deficencies which need adds x,y and z to treat, and the next one needs say more x but less y and z. So even in the same oil grade, the adds can vary over time.

 

[Audi Junkie]

5w-20 typically has more moly in some brands. I used to mix viscs from the same product line, not so much anymore, just if really needed.

 

[mechtech2]

I like to keep the same engine oil in the crankcase. It's a good general practice.
With mixed concoctions, I don't think the additives are actually destroying each other, but that the present additives may not be allowed to do their job fully and to the best advantage.

A terrible analogy is that two five foot ladders will not reach as high as a ten foot one.

That said, if I had to add another brand of oil to a car engine, the only thing I would worry about is the oil level.

 

[jldcol]

Do you mean to mix brand x 10w30 and brand x 10w40 together, would there be additive clash? I believe(my opinion) that oils are to be mixable(actually miscable) by design, and that means mix oil a and oil b to get a single product, and something that will not later seperate into differential layering. That is the base oil, those add packs are there to shore up this base oil, things it could not otherwise do, at least for very long. These adds may/do need a balanced ratio between different things, and thus adding another different ratioed product, well the mix is some other proportioned thing, and not/less like the originals, and thus should be less well suited to the intended use. Staying with the same brand is better than mixtures between them, but no guarantee? of optimal product. I use a 50/50 mix of 10w30 and 10w40 of the same manu to use up some cheap finds I made, and the mix lessens oil useage compared to the thinner one and is thinner than the thicker one, for more mpg's. Compromised stuff, yes but it is what I got.

 

[Audi Junkie]

Yes, that makes sense, but the additive proportions are not a linear relationship, more like a "synergy" (excuse the pun).

If you look a the different requirments for API specs, going by the various "grades", it IS quite clear the oils themselves are very different from 30 to 40 and so on. A 30 weight has completely different additives and base oils to do a quite different task...mpg, emissions and such are very different for a 5w30 Starburst to a 10w-40 or 20w-50! They are different by spec and by composition. Want to mix 5w30 and 10w-30 of that same brand? Fine, that's as close as you will get formulation-wise.

That is all factual concern, but my personal opinion is that we are all on this forum to perfect and maximise our engines and oil...mixing them willy-nilly IS NOT OPTIMAL!

I even sort my stashed oil by date codes and use from the same batch together (earliest to latest, of course).

 

[webfors]

Agreed. Don't mix if you can avoid it. There will be no benefit, and there are possible pitfalls as mentioned above.

The manufacturer creates their products with the assumption that you will *not* be mixing.

 

[jldcol]

I wholeheartedly agree with batch mixing, makes sense also energy conserve to EC only other oil also sensible like to like or at least more alike to more alike. The 2 I use are both SL and non EC and are syn-blend also, forgot to mention also use 5w30 in the mix, all in one series of jugs, non labeled so the oversite, and the 5w30 is "syn" SL, likely all group 3. This is a winter mix so only in for 4-5 months then gone.