Oil Discussion #101 - Street, Highway and Drag (not Track)

[TopJimmy]

There's been a hundred threads here on Engine Oil, but most focus on Track use. Oil on track usually experiences high RPMs for prolonged periods, engines are fully warmed up before use, and oil is changed frequently.

Oil used for Street, Highway and Drag experiences conditions almost opposite from track. Street use includes daily driving, and some start the car and just go with the engine cold. Highway and Drag racing has short periods of maximum acceleration. Worst case here is at the drag strip where someone didn't remember to warm up first, or shutting down immediately after a run.

In this thread I'd like to discuss topics like:
1) when to stick with stock BMW TPT oil
2) better oils for standard daily-drivers
3) better oils for stock internals and stock turbos, but used for highway 60-130 or 1/4mi drags
4) same as above with aftermarket turbos, and harder highway/drag use
5) how E30-50-85 contaminates oil and shortens your oil change interval (OCI)

We're not going to get into extending OCI with Blackstone or lab testing. Most of us simply change every XX thousand miles so we will try to stick to mileage.

I would like to introduce our "Wizard of Oilz" edycol who has immense knowledge of oil properties, stocks, additives, certifications, and how these come together to protect our engines.

[TopJimmy]

Let's start with Topic 1, when to use "stock" BMW Twin Power Turbo (TPT) 0W30.

TPT carries the BMW LL-01 FE certification for increased fuel economy, and is a special blend manufactured by Shell Oil. This is quality oil intended for daily driving and spirited use, and the winter 0W rating allows faster flow for some cold startup protection. The additives work well for anti-oxidation, anti-foam and anti-shear.

Many of us are covered under a maintenance plan where the dealership changes engine oil and filter at the 10K intervals, but we want extra protection by changing more frequently (at 5K) then sticking with TPT is a good choice. This way you're not mixing additives from different brands/types when you change oil. Remember we have an oil cooler circuit that doesn't drain, and the engine has many passages and tubes, so this "carryover oil" can be up to 20% in our S55.

Edy, what other points should be said about BMW TPT for daily and street use, and what did I mess up?

[edycol]

Thank you TopJimmy for starting this topic.
Before I get into why to use TPT 0W30 and why not, I want to address some basic stuff that people usually get wrong by watching YouTube videos or being exposed to marketing by some oil blenders.
In 1990's European manufacturers started organization called Association des Constructeurs Européens d'Automobiles or ACEA (European Automobile Manufacturers Association). Among things ACEA does is also setting up oil requirements. ACEA members figured in the 90's that API became obsolete and since API is the lobbying arm of oi blenders, car manufacturers thought they are too lenient to demands that engines pose on oils. So ACEA set up a sequence where oil blenders must follow if they want designation like ACEA A3 (gas engines: A, Diesel: C). Then manufacturers developed their own approval process that was based on ACEA, just more stringent.
That is what BMW LL01 is. It is BMW approval that was introduced in 2001. However, since then LL01 approval was updated several times, and the last time was in 2018. Mercedes has its own approvals and generally, they are most comprehensive in the industry. Porsche has too and usually, it is the same as VW approvals, except A40. Porsche approval A40 is not the toughest in the industry but has a specific test based on 8hrs simulation on Nurburgring.
So, why these approvals? Basically, it is to help the owner to choose oil. If oil is approved, buy it, use it! Approvals are cheap to obtain (development of oil is not). Many oil blenders who do not have approvals claim it is too expensive. It is not! It is their excuse for not obtaining approval. It has to be said that some oils cannot be approved as they are specialty oils (track or race).
Anyway, let's go back to LL01. ACEA A3 has a basic requirement when it comes to wear and protection, and that is a minimum HTHS of 3.5cp. What is HTHS? HTHS is High SHear-High Temperature. Resistance of oil to temporary of permanent loss of viscosity. Usually HTHS of 3.5 is achieved with so-called "heavy" XW30 oils or light XW40 oils. BMW also requires HTHS of a minimum of 3.5 for LL01 and max 4cp. This range is a kind of golden medium between protection and resistance as higher HTHS means more resistance and with that performance suffers and the heat goes up.
LL01 was BMW's go-to oils until 2016 when in North America they introduced LL01FE. FE is exactly what you think it is: Fuel Economy. The thing is, the way CAFE requirements are set up, lighter oil means less resistance means very small gains in mpg. But enough to have 1mpg bump awarded by EPA, and when you have a huge fleet of vehicles, every mpg counts. So BMW is now using this LL01FE in M3, and 0W20 in other vehicles. HTHS is dropped to a minimum 3cp, and a maximum 3.49 for LL01FE.
So, what is the advantage of LL01FE over LL01?
LL01FE is a lighter oil. KV100 (Kinematic Viscosity at 100c. That is what determines grade) is in mid 10cst (XW30 oils have KV100 9.2 to 12.5) and HTHS is usually at the lower end of 3cp. That means less resistance. That also means that regardless whether oil is 0W30 or 5W30, it will have easier flow during the warm-up phase and is a much better option for short trips, extreme cold (winters in AK, MN, ME, ND, MT), and mpg. It is also a better option for those that drive strictly on HWY and are not interested in pushing car to the limits while driving on local mountain roads etc. HWY driving is generally least stressful on oil.
And in the end, if the owner's manual says only LL01FE, then use it bcs. warranty.
When to use LL01?
LL01 is the approval that is geared for performance and wear protection. Yes, it has fuel economy requirements by BMW, but nothing major. The focus here is performance.
The minimum HTHS is 3.5cp. That means oil can be XW30 and usually, that means so-called "heavy" XW30 oils, meaning KV100 is definitely above 11.5, mostly around 12cst if not a bit higher. Or it could be XW40 oil (KV100 for XW40 oils is 12.5 to 16.5cst). Most XW40 street oils are in HTHS range of 3.6cp to 3.9, maybe, very rarely 4cp. Some of the best oils in the world are in this category of HTHS min. 3.5. They are much more common than LL01FE oils. They usually carry a slew of European manufacturer's approvals from MB, VW, Porsche, BMW etc. While they are not energy conserving like FE oils, the mpg penalty is not significant and probably on street, you will never notice the difference. They can be significantly heavier than FE oils which means a longer warm-up phase. But generally, engines like S55 are geared toward these oils.
If your manual says you can use LL01 oil, use it! Unless you worry about 1% penalty in mpg!
Now, BMW in 2018 updated all their approvals and LL01 approval now does not recognize 0W30 and 0W40 oils due to increased oxidation requirements (to bump OCI).
This means that three of the probably best oils in this category, Castrol Edge 0W30 and 0W40, and Mobil1 0W40FS lost this approval. If you are out of warranty, these oils are still an excellent choice (if not best when it comes to Castrol) in S55 engines.

Now, the question of mixing oils. First, all API oils can be mixed. One of the basic requirements by API is that oils can be mixed with each other. But, you really do not want to have 2qt of Castrol, 2qt of Mobil1, 2qt of Shell/Pennzoil.
Problem are additives. Additives are either anti wear, anti oxidation or cleaning. They must work with each other and each oil has carefully balanced additive package. Leftover oil in oil coolers is really not an issue, but, adding additives to "improve" anti-wear performance of an oil etc. is really, really not smart. Why? For example ZDDP, THE MOST important anti-wear additive (Zinc dialkyldithiophosphates) is basically an acidic additive. Other additives are anti acidic cleaning additives. So yes, they are contradictory to each other. What does that mean? That means the oil blender has to have a careful balance between ZDDP and other additives. Now you add ZDDP additive and you messed up that balance or more cleaning additives. So by all means, you just want to stick to the oil you put in the sump and nothing else.
I mentioned above terms like HTHS, and I want to elaborate on that.
HTHS is the most important variable when it comes to protecting the engine. It is hydrodynamic value. HTHS is what matters, NOT grade. Some XW30 oils have higher HTHS than XW40 oils. Key is in base stocks, polymers etc. HTHS is what protects piston rings, rod bearings, turbo bearings. Higher HTHS, more protection. But you don't want to go crazy on that too.
When HTHS is not enough, when engines are so loaded that there is break-in oil film, what then? That is where ZDDP comes to play. ZDDP will form a glossy film on engine components that will protect mostly piston rings and cylinder walls from damage. It is highly unlikely (nor it should happen) that ZDDP needs to be relly on when it comes to rod bearings. Hydrodynamic properties of oil should be enough at those spots.
How good hydrodynamic properties of oil depend on oil temperature. M3/4 has tremendous oil cooling capabilities, so these LL01 oils with HTHS 3.5 to 4cp are more than adequate.

[arucano]

Great explanation.

[TopJimmy]

edycol, would you comment on Topic #2 - Better oils for Daily Drivers (no highway racing or short-term abuse yet)?

It would be great to first have a short list of the oils you approve of, and then some info on why these are recommended.

Thank you as always for sharing the knowledge.

-TJ

Disclaimer: nobody can hold Edycol responsible for providing his input, you make your own choices.