BMW recommends Oil Changes every 15,000 miles. Here's a kind of "in depth" on motor oil and how they can pull that off:
Stay with the older spec'd OILS as the newer specs are designed to meet newer emissions standards, there is an inverse relationship between engine protection and MPG's / environmental concerns.
Go with "ESP" if you want more MPG's (Greener alternative) over better engine wear protection which is found in oils with high levels of ZDDP.
Lower engine protection equals more MPG's. Why? Because mass (zinc,(ZDDP) equals protective film that "slightly" lowers your MPG's but mostly the "Green Party" people do not want zinc in the oils but that's what protects them.
ZDDP is the antiwear additive to look for:
The antiwear additive ZDDP (Zinc DialkylDithioPhosphate) activates as it decomposes at hot metal surfaces and forms a glass-like protective layer on the metallic surface.
The active ingredient phosphorus which is added through a component called ZDDP.
If you prefer a product with a higher level of anti-wear performance, there are a number of Mobil 1 synthetic oils that have higher levels of phosphorus.
Remember that BMW LL-01 requires HTHS to be above 3.5. Most synthetic oils today fall well below that requirement. Mobil 1 0W-40's HTHS is 3.8 so it is a great buy at $24.95/jug.
This test is a simulation of the shearing effects that would occur within an engine. In fact, it's actually designed to simulate motor oil viscosity in operating crankshaft bearings.
Under high stress conditions where shearing can occur, the VI Improvers (polymers) break down. As they do, the viscosity of the oil decreases. This is what the High Temperature/High Shear test checks for.
The HT/HS test is measured in Centipoise (cP) as the Cold Crank Simulator test is. However, in this case, because you're hoping for the least loss of viscosity with an increase in heat and stress, you want the cP value to remain high.
HTHS is a balance between fuel economy and protection. Too high of an HTHS and you lower fuel economy, too low, and you reduce wear protection.
Within the oil industry, the big issue is with low HTHS figures (those below 3.5). As Lubrizol states:
A critical issue for the oil industry is how misapplication of low HTHS viscosity oils will be avoided. The use of low HTHS oils will save fuel in engines designed for their use but could lead to excessive premature wear in some engines.
Engine manufacturers are evaluating their hardware to see if engine durability, especially for ring and liner scuffing is an issue with low HTHS viscosity oils so they can take advantage of the engine lubricant delivering improved FE to meet the new US Environmental Protection Agency (EPA) and National Highway Traffic Safety Administration (NHTSA) FE and GHG requirements
So, if you're trying to squeeze every mile out of your gallon of gas, then go with a sub 3.5 HTHS oil, if you're most concerned about wear on the internal components, then seek out an oil with >3.5 HTHS.
Why offer <3.5 HTHS oils?
The drivers behind lowering HTHS viscosity are new global governmental regulations to improve fuel economy (FE) and lower greenhouse gases (GHG) in new vehicles. Lower HTHS viscosity tends to improve FE and lower GHG but higher HTHS viscosity affords better wear protection so a careful balance must be found when formulating an engine oil.
Avoid any oil with the FE designation "Fuel Economy" on the packaging.
So we know to look for motor oil that is > 3.5 HTHS.
What about viscosity?
The BMW 5W-30, LL-01, at 100 Celsius (212 Fahrenheit) = 12.2 cSt viscosity rating; (heavy weight = 10 - 12.5cSt@100c) (thin weight = < 10 cSt@ 100c)
Mobil 1 0W-40 = 14.3 cSt @100C
Their Mobil 1 5W-30 Extended Performance = 10.2 cSt @ 100C (A much lighter weight oil than 0W-40)
So, folks, I am telling you, that Mobil 1, 0W-40, at Walmart for $24.97, 5 quart jug, is highway robbery.
It might (slightly) rob you of some MPG's, but, come on! We're trying to save that $18,000 motor from unnecessary wear; aren't we?
The viscosity of a fluid is a measure of its resistance to gradual deformation by shear stress or tensile stress. For liquids, it corresponds to the informal notion of "thickness". For example, honey has a higher viscosity than water.
I am in favor of engine bearing protection over MPG's.
With Mobil 1 0W-40, you have a lot of oil "thickness" between surfaces at high temp's.
I vote "yes" for that!
Stock up for ALL of your vehicles at this price. I certainly have!
Worried about Cold Starts? 0W-40 has a pour rating of -45 degrees celsius.
So you are covered on those cold Northern nights.
Mobil 1 0W-40 = HTHS of 3.8 (BMW requires 3.5 min);
Viscosity of Mobil 1 0W-40 = 14.2 at 212 Fahrenheit while (BMW requires 12.3).
In other words, Mobil 1, 0W-40, kicks axx on BMW's LL-01 spec's.
Now take this data, and compare to your favorite Castrol oil blend/mix/packaging.
Go to their (Castrol's, etc) web site and review their MSDS data sheet on the specific oil you are contemplating.
Castrol Edge with Syntec Power Technology 0W-30: 12.2 cSt @100 celsius
Castrol EDGE Professional A3 0W-40: 13.5 cSt @ 100 celsius
Castrol EDGE 0W-40 A3/B4: 13.3 cSt " "
Castrol SLX Professional OE 5W-30 12 cSt
Castrol Tec II 5W-30: 10.6 cSt
Castrol EDGE 5W-40 U.S.: 14.28 cSt
Castrol Power RS Racing 4T 5W-40: 13 cSt
Liqui-Moly Synthoil Energy SAE 0W-40 Viscosity at +100 °C : 14 cSt
Liqui-Moly Synthoil Longtime SAE 0W-30 Viscosity at +100 °C : 10.1 cSt
Liqui-Moly Synthoil Longtime Plus SAE 0W-30 Viscosity at 100 °C : 9.6 cSt
Liqui-Moly Synthoil High Tech SAE 5W-40 Viscosity at 100 °C : 14.1 cSt
What a difference in viscosity across the oils. From a very thin 9.6, to a heavy 14.1 cSt.
But on the shelf, they all look good.
You want MPG's? Go with the 9.6
You want heavy protection? Go with 14.1 cSt
BMW wants 12.5 cSt minimum
Total QUARTZ 9000 5W-40: 13.6 cSt, HTHS ?
Total QUARTZ ENERGY 9000 0W30: 12.18 cSt, HTHS ?
Total QUARTZ RACING 10W-50 17 cSt, HTHS ?
I do not work for Exxon/Mobil nor Walmart, but every once in awhile, they offer incredible bargains to the public. Mobil 1, 0W-40, is such a bargain.