Calcium VS Magnesium

[buster]

It's interesting how most of the top tier PCMO's used mostly all Ca for the primary detergent. The move to Mg was to lower the SA. Whethe it's better/worse I don't know. I've always thought the all Ca was better, as it was found in Amsoil, Redline, and Mobil 1. However, Shell has used it and so has Maxima and other oils.

Mobil 1 0w40 has a good amount of Ca. No Mg. It also has a higher SA @ 1.3%. Amsoil is similar.

It's possible that an all Ca based detergent could be better, but I'm not so sure.

 

[Garak]

Originally Posted By: Gokhan
If that's the case, Shell has completely changed their detergent philosophy. This is what they used to say:

If Shell is looking to meet certain ACEA E sequences, is possible their choices might be fewer than in the past? Having a high TBN and a low SA as required by some of those sequences might not be easy, and perhaps magnesium makes it easier.

 

[MolaKule]

Originally Posted By: buster
Ashland is using a Lubrizol additive package which uses Na as part of it's detergent system.

Castrol and Mobil, and many other diesel oils use Mg/Ca combinations. That I'm pretty sure is an Infineum system. They are using Mg to lower the slufated ash.

Where Gokhan and Voltmaster are wrong, is their unscientific assumption that just because an oil has Mg it is therefore inferior. Not so.

Non-metallic detergents are being used that will not show up in a VOA. Also, the level of Mg being used is very small. Nothing to worry about at all. Let the industry tests prove how good the product is.

Advanced additive technologies such as salicylate detergents, enhanced low S/P anti-wear and new antioxidant technologies are being used.


Magnesium salicylates can offer a reduction in total sulphur content, maintain antioxidant stability, and prolong TBN durability.

 

[Gokhan]

I think buster and Garak are right that the only reason some oils started using magnesium lately is to keep TBN still high while lowering the sulphated ash.

Yes, calcium is better, but with today's oils offering higher-quality base oils (less acids generated due to base-oil oxidation) and gasoline having less sulfur (less acids generated due to sulphation) and engines burning cleaner (less acids generated due to nitration), magnesium, despite being inferior to calcium, is probably sufficient to keep the "TBN minus TAN" high enough for reasonable OCIs. So, it really doesn't matter at the end for reasonable OCIs.

In my case, with the TGMO 0W-20 SN that has all-calcium detergent and 85 Corolla, my TBN dropped by only 0.95 and TAN increased by only 2.25 in 5170 miles. Low-sulfur gasoline in California helps though.

 

[CarbonSteel]

I ran M1 AFE 0W-20 for 15.3K miles and it produced the best UOA to date in my FX4. The starting BN was 9.0 and the starting AN was 2.9. The ending BN was 2.9 and the AN was 5.0. Obviously, AN crossed BN, but I am not so sure that the instant AN crosses BN that it is detrimental to the engine. Granted, I changed the oil at that point (mostly due to curiosity on the oil and filter), but when the AN is within 4 points or so of BN are we really risking accelerated wear? It is my understanding that 8.x is the finite line for when wear begins to occur with high AN.

What say you?

 

[Gokhan]

Link to your UOA?

 

[SilverC6]

Originally Posted By: MolaKule


Magnesium salicylates can offer a reduction in total sulphur content, maintain antioxidant stability, and prolong TBN durability.


Isn't this why magnesium shows up in most extended drain oils like M1 EP and the Euro spec LL-01 oils?

 

[CarbonSteel]

Originally Posted By: Gokhan
Link to your UOA?

Here are all 19 of them to date (every OC has been UOA'ed).

 

[Gokhan]

Originally Posted By: 2010_FX4
Originally Posted By: Gokhan
Link to your UOA?

Here are all 19 of them to date (every OC has been UOA'ed).

Wow, how can you drive 15000 miles in a month?!

Very nice table, and UOA is looking good.

Note that most labs, especially Blackstone, underestimate TBN because they use an older ASTM test method. Your actual TBN could be higher by 1 or 2. WearCheck uses the newer, accurate ASTM test method.

The critical thing to look at is the "TBN minus TAN". I wouldn't say wear starts immediately when TAN exceeds TBN, but I think it starts somewhere around where TAN exceeds TBN by 3 or 4. Again, also keep in mind that Blackstone and most other labs underestimate TBN perhaps up to 2. Ideally I would like to keep TAN below TBN -- if not, less than about TBN + 2 or TBN + 3 -- but also keeping in mind that TBN might be underestimated (especially by Blackstone).

 

[CarbonSteel]

Originally Posted By: Gokhan
Wow, how can you drive 15000 miles in a month?!

Note that most labs, especially Blackstone, underestimate TBN because they use an older ASTM test method. Your actual TBN could be higher by 1 or 2. WearCheck uses the newer, accurate ASTM test method. The critical thing to look at is the "TBN minus TAN". I wouldn't say wear starts immediately when TAN exceeds TBN, but I think it starts somewhere around where TAN exceeds TBN by 3 or 4. Again, also keep in mind that Blackstone and most other labs underestimate TBN perhaps up to 2. Ideally I would like to keep TAN below TBN -- if not, less than about TBN + 2 or TBN + 3 -- but also keeping in mind that TBN might be underestimated (especially by Blackstone).

You mean 5,000 miles in a month?

I think we are saying the same thing perhaps in a different sort of way. I agree that TAN needs to be a fair amount higher than TBN and this concept seems to track with reality. For example, on my 10K reading, if we need to add 2 to the TBN to have the true number then it would be 4.2BN versus 4.3AN and likewise on the 15K run--4.9BN versus 5.0AN.

But TBT, I have read here more than once that Blackstone's TBN numbers are always higher than other labs (but I guess that could assume the TAN is off as well?). I did one UOA with Wearcheck and Blackstone on the same sample (split in half) to qualify Blackstone's numbers and I do not recall what the differences were. I need to dig those up...

 

[Revelate]

Originally Posted By: Gokhan
As far as I remember, the only reason why the all-calcium oil performed poorly in the Chevron Oronite paper was that it had a very low initial TBN.

Shell believes in all-calcium oils, even for HDEO. Other oil blenders experiment with magnesium now and then.


If you check the Oronite research paper (or the machinery lubrication link which is more easily read)the Mack T-9 testing procedures were done with a low TBN reference oil of all calcium, a low TBN all magnesium oil, then a low TBN Cal/Mag (3:1 ratio), and finally a high TBN Cal/Mag (6:1). The low BN pure Ca oil consisted of a BN of 6.08, while the low TBN pure Mg oil was at 6.97.

Now, the pure Mg oil has a TBN of only 14% higher than the pure Ca oil, but once again its important to note that the all Mg oil outperformed the all Ca oil in all testing procedures except in total acid number, but even with the TAN being higher in the all Mg oil, it still outperformed the all Ca oil in remaining TBN, lead content, and oxidation, which appears to indicate magnesium alone outperformed an all calcium formulation in the same testing.

I completely agree that the rule of thumb of TBN-TAN should be used and makes perfect sense, and based off what I've read a high content of Mg may not be as useful in extended interval oci's like Amsoil's 24K mile since it could lead to an artificially high TBN because it's not neutralizing as many acidic byproducts like Ca can, but from the research it appears Mg is at least an equal if not have a slight upper hand when compared to Ca. Again, I don't mean to sound argumentative and am open to any other research or updated studies that anyone can offer/reference.

Indeed shell believes in an all calcium formulation for their PCMO's along with their Rotella T oils in 15W40, and 10W30, but in their more expensive full syn. T6 5W40 they use a Ca/Mg blend with Mg concentrations over 50%.

Buster, I agree with ya. It's tuff to say which is better, since based off the testing they're both close performers, and like u said, Shell is using in their T6, Mobil 1, along with EP & HM use it (their 0W40 being a notable exception), Castrol edge, etc. One of the drawbacks i'm sure is the extra cost incurred by using Mg, especially in more economically priced standard petroleum oils.

MolaKule, I read in another post that you work in the Petroleum Industry and was curious if you had any input as to the cal/mag debate and why companies might preference certain detergents based off price/performance values or any other data?

 

[Solarent]

Originally Posted By: MolaKule
Originally Posted By: buster
Ashland is using a Lubrizol additive package which uses Na as part of it's detergent system.

Castrol and Mobil, and many other diesel oils use Mg/Ca combinations. That I'm pretty sure is an Infineum system. They are using Mg to lower the slufated ash.

Where Gokhan and Voltmaster are wrong, is their unscientific assumption that just because an oil has Mg it is therefore inferior. Not so.

Non-metallic detergents are being used that will not show up in a VOA. Also, the level of Mg being used is very small. Nothing to worry about at all. Let the industry tests prove how good the product is.

Advanced additive technologies such as salicylate detergents, enhanced low S/P anti-wear and new antioxidant technologies are being used.


Magnesium salicylates can offer a reduction in total sulphur content, maintain antioxidant stability, and prolong TBN durability.


I don't have much time today to draft a complete explanation, but I will try to get something good soon.

IMO it comes down to selection of multifunctional properties of the detergents. We tend to favour calcium detergents because they can help improve the alkali reserve. As Molekule pointed out if you are looking to reduce sulfur content (as in Hddeo) then magnesium salicylates are a good alternative. Of course detergent selection also influences all the other parts of the formula.

 

[Jasper8146]

When I was using Valvoline Synpower, the UOA's came back with elevated levels of sodium and those high levels did mask whether or not coolant was in my engine oil. I had a concern about that due to the oil level increasing. That said, am not aware of any other negative consequences of sodium add pack.

 

[Revelate]

Originally Posted By: Jasper8146
When I was using Valvoline Synpower, the UOA's came back with elevated levels of sodium and those high levels did mask whether or not coolant was in my engine oil. I had a concern about that due to the oil level increasing. That said, am not aware of any other negative consequences of sodium add pack.


Sodium is used in oil formulations (most commonly found in Ashland products like Valvoline & Napa) as yet another detergent additive usually found in combination with Ca. There's nothing inherently wrong with it as a detergent, although it's not as popularly used among other oil manufacturers.

If you're worried about increasing coolant levels in your oil, as a previous post said sodium will usually be accompanied via an increase in potassium. U can also check sodium levels in your UOA and compare it to PQIA's VOA of Synpower to get a general idea of what to expect level wise (461 PPM) and look for higher than average increases.

http://www.pqiamerica.com/March2013PCMO/Marchsyntheticsallfinal.html

 

[Garak]

Originally Posted By: Gokhan
I think buster and Garak are right that the only reason some oils started using magnesium lately is to keep TBN still high while lowering the sulphated ash.

If you look at Delvac 1 ESP 5w-40 and the Rotella 5w-40, they meet many of the same ACEA specifications. They need to have a TBN of 10 or greater and SA of 1% or less.