What do we lose with API SP oils and older engines?

[shortyb]

Specifically in the VW/Audi speced 502.00/505.00 requirements. I know the SL, SM and SN oils were higher in some adds that may have been viewed as beneficial to the older engines, such as calcium, zinc, phos etc. I still haven't figured out what, if anything, we gain/lose with move to SP, other than the lower calcium for LSPI prone engines. I know if they meet approvals, then from that standpoint it's moot. Just wondered what it really means moving to SP for older stuff.

 

[JGmazda]

Good question. I also would like to know. I've got a 22yr. old Buick and oil formulation has really changed in twenty years.

I'm wondering if newer formulations create more wear (Less zinc, moly etc.) than the older oils. ?

 

[skyactiv]

VOA's and UOA's don't show all the additives which can be in modern oils.

 

[Petr]

You can have a look into the Afton Book where individual tests are defined. I have learned that the requirements for oil quality, engine cleanliness, and engine protection are usually increasing. This way the backward compatibility from API SP to API SL is assured -API SP is better than API SL. Additionally, the recent research improves knowledge of tribofilm formation, robustness, etc. Therefore new oil formulations benefit from that additional knowledge.

We have 20+ year oil toyota where API SJ was prescribed. The car was filled-in with API SJ, API SL, API SM, API SN oils and is likely to get some API SP oil in the future.

Moly is mostly for friction reduction and much less anti-wear. Moreover, moly was found to compete with ZDDP therefore one cannot say that high moly is better than low moly or high zinc is better than low zinc. It is not that easy.
I like oils that have some moly, some boron and some demanding approval.

My safe bet for very good engine protection is oils with one of the MB 229 approvals. If you can find any oil that has valid MB229.5 approval you can be sure you have an excellent oil that is highly likely to meet or exceed the protection provided by the best oils that were available 15-20 years ago.

 

[twX]

Compared to API SN, API SP requires better performance in the fuel economy and high temperature piston deposits tests. The valvetrain wear test was replaced with a different one. That's about it, besides the LSPI and GDI timing chain wear tests.

The GM Dexos 1 Gen 3 certification has a lot more requirements on top of API SP, notably much more stringent requirements for passing the sludge test, and a lower maximum NOACK (12.5% vs 15%). There are also additional tests for wear, fuel economy, high-temp piston deposits, that may be more stringent than the tests required for API SP. There's also a turbo deposit test that has no equivalent in the API standards.

MB 229 and VW 508/509 require even lower NOACK than Dexos (11%). MB 229 also requires a minimum TBN of 7.5 and higher minimum phosphorus than API SP. As far as I can tell, these euro standards don't require any unique engine tests, just some spec sheet requirements.

So while there's not much benefit to API SP over SN for older engines, I think that an oil with API SP and Dexos 1 Gen 3 does add a lot.

 

[OVERKILL]

Specifically in the VW/Audi speced 502.00/505.00 requirements. I know the SL, SM and SN oils were higher in some adds that may have been viewed as beneficial to the older engines, such as calcium, zinc, phos etc. I still haven't figured out what, if anything, we gain/lose with move to SP, other than the lower calcium for LSPI prone engines. I know if they meet approvals, then from that standpoint it's moot. Just wondered what it really means moving to SP for older stuff.

Phosphorous has been restricted on xW-30 and below grades since API SL. There is no limit on zinc.
Calcium is reduced (and magnesium increased) since API SN+, which was to help with LSPI

An API SP 0W-40, other than having a different detergent package (more magnesium, less calcium), will have the same level of phosphorous as it did when it was API SL.

 

[OVERKILL]

Moly is mostly for friction reduction and much less anti-wear. Moreover, moly was found to compete with ZDDP therefore one cannot say that high moly is better than low moly or high zinc is better than low zinc. It is not that easy.

Moly is synergistic with ZDDP, it improves both wear control and friction reduction. Of course the dose required will vary depending on other components and the type of moly being used.

 

[Petr]

Overkill: I am aware of that document. For this reason, I like oils that have at least some moly. On the other hand, I was wondering, why some manufacturers used high concentrations of moly, even if they used dimer, some concentrations were surprisingly high (e.g. 600+ppm).

I found some interesting answers in the paper below, sections "3.1. Friction analysis", "3.2. Tribofilm thickness" and "3.4. Wear analysis" were interesting (at least for me):

https://www.sciencedirect.com/science/article/pii/S0301679X2200010X

 

[kschachn]

So are you suggesting that manufacturers have altered their approval requirements so that the oil can also gain an API license?

 

[OVERKILL]

Overkill: I am aware of that document. For this reason, I like oils that have at least some moly. On the other hand, I was wondering, why some manufacturers used high concentrations of moly, even if they used dimer, some concentrations were surprisingly high (e.g. 600+ppm).

I found some interesting answers in the paper below, sections "3.1. Friction analysis", "3.2. Tribofilm thickness" and "3.4. Wear analysis" were interesting (at least for me):

https://www.sciencedirect.com/science/article/pii/S0301679X2200010X

I think the obvious limitation of that study is that they used a fully formulated oil minus an FM and then dosed it with a specific moly compound. In my discussions with @High Performance Lubricants, there is an optimization process for each base oil blend and additive package that is then tested and further refined with a group of FM's in order to achieve the best results. This means a combo of moly trimer, dimer and even tungsten (and potentially titanium FM's as well).

Since you are familiar with the Infineum presentation, you know they contrasted the performance and characteristics of different moly types, but never blended dimer with trimer because the presentation was about the performance advantages of trimer over dimer.