Oil for a Mercedes aluminum cylinder engine

[GregGood]

I've been doing a lot of reading lately about oils, but it is all concerned with engines that have cast iron cylinders.

As I understand it the ZDDP is a polar molecule and is attracted to ferrous metals.

What about an aluminum cylinder wall like on my E430? What type of oil would protect the cylinder walls and piston skirts on it the best?

Thanks.

 

[tom slick]

I'd assume the cyl walls are plated with a much harder substance making lubrication much less of an issue.

 

[berlyn]

 

[Mark888]

Originally Posted By: GregGood
I've been doing a lot of reading lately about oils, but it is all concerned with engines that have cast iron cylinders.

As I understand it the ZDDP is a polar molecule and is attracted to ferrous metals.

What about an aluminum cylinder wall like on my E430? What type of oil would protect the cylinder walls and piston skirts on it the best?

Thanks.

Probably the one recommended by Mercedes.

 

[Gary Allan]

Well, you can use M1 with confidence. Since it's made of aluminum ..you don't have to worry about all the Fe shedding that M1 is notorious for....

j/k

 

[Kestas]

The alloy used in this application is essentially a hypereutectic Al-Si alloy. This means that there are relatively large particles of silicon, called "primary silicon", in the aluminum matrix. After machining, the wall surface is prepped in such a manner that the softer aluminum is polished away, making the silicon stand proud in relief. This provides an incredibly hard and wear resistant surface for the piston and rings to ride on, and oil is retained where the aluminum is polished away. Basically the best of both worlds.

With proper maintenance, I heard these cylinder walls can run 500K with virtually no wear. But if something traumatic should happen to the walls, repair (or reconditioning) is incredibly difficult. I doubt the average mechanic or machine shop is capable of repairing these cylinder walls.

What oil does Mercedes recommend? I can only imagine their tribologists studied this surface in detail before recommending a lube regimen.

 

[mechtech2]

The Germans invented 'Sham Wow' cloths.
They make good stuff, you know.

As to the cylinder walls of this engine, I would not second guess the recommended oil by the mfr..
This type of cylinder was used in the Chevy Vega [Cosworth] about 4 decades ago.

 

[GregGood]

I've been running the German Castrol for approximately the last two years.

I was wondering if the AW (ZDDP) packages normally found in oil would work on aluminum as well as cast iron. And if not, would an oil made from esters, like Motul, be a better choice?

I love this car and plan on driving this car until the wheels fall off.

Thank you for the responses and the welcome.

Greg

 

[HTSS_TR]

I have 2000 E430 I bought new in April 2000. The car had M1 0W40 the first 8 years/90k miles using FSS for OCI's at around 12k miles/1 year.

Last spring (2008) I tried PP 5W20 and found that the engine noise was much quieter with thinner oil. I went to Vegas last July 04 and got stuck at Death Valley for 3 hours with ambient temp above 120F, but the coolant temperature was never above 98C with air conditioning ran at full blast. The PP color was very dark after only 1k mile and almost black after 3k miles, I think PP 5W20 do some cleaning after 90 k miles with long OCI's even with good synthetic oil such as M1 0W40.

Because of this severe condition, I changed PP out with only 6k miles with Delo 15W40. Engine noise was as noisy as with M1 0W40 and gas mileage drop down as with M1 0W40. Gas mileage was 4-5% better with PP 5W20.

Last Dec I changed to 5qts M1 0W20 + 3qts M1 10W30, engine noise is reduced substantial compares with either M1 0W40 or Delo 15W40, about the same as with PP 5W20. Gas mileage is back to about PP 5W20, I just made a 140 miles round trip with 4 people and luggage, about 80% highway and got 26.6 mpg with average speed of 46 mph. The EPA rating is 18/24 City/Hwy.

The conclusion is, my particular E430 like thinner oil. Engine is much quieter and accelerated much faster while consumed much less fuel.

My next OCI will be with Synpower 5W20 I bought on sale (and rebates) for less than $1/qt. All the oils I have in stock were bought on sale with rebate(s), such that I have several brand names and I don't think brand matter. The main effect on engine performance is viscosity and I and my engines love thinner oil.

 

[tig1]

Don't assume that just because your water temp was at an exceptable temp that all was well. Your crank case temp may have been gone through the roof deminishing the oil integrity. Believe it or not MB engineeres know what they are doing when they say use 0-40 synt oil that meets their spec.
You have a nice car, don't skimp a dollar are two on oil.

 

[GregGood]

HTSS TR, I'm skeered to run 20w down here in Houston, especially in the summer. I think for now I'll stick with the Euro Syntech as its on MB's 229.5 list.

Both of the oil people I know have told me that the AW additive package in the oil will do nothing to protect the hypereutectic aluminum cylinder walls in an MB engine. Oil film strength is my only protection.

 

[JAG]

No, you're covered by at least ZDDP additives. See here: http://www.springerlink.com/content/n28l5411wr7w422k/

Quote:
Understanding the lubrication of aluminum–silicon (Al–Si) alloys (>18 Si) under conditions similar to those in the cylinder/bore system is vital to determining their applicability to current engine designs. A novel investigation of the location of zinc-dialkyl-dithiophosphate (ZDDPs) antiwear (AW) film formation on an Al–Si alloy has been performed using X-ray absorption near edge structure (XANES) analysis, X-ray photoelectron emission spectroscopy (X-PEEM), and imaging nanoindentation techniques. A study of the initial stages of wear (10 min) to prolonged rubbing (60 min) was performed. The findings show that the film forms primarily on the raised silicon grains and is consistent with a zinc polyphosphate glass. The film has an elastic modulus of ~70 GPa and a similar elastic response to a ZDDP AW film formed on steel under the same conditions. This provides the first direct observation and characterization of a ZDDP antiwear film on Al–Si alloys using spatially resolved chemical and mechanical techniques at the nanoscale.

 

[GregGood]

Thank you JAG. That is good info. I will pass it along to those that may be interested.