Castrol 10W-60 in BMW Z4 M Coupe

[JAG]

I was at a BMW dealership today and oddly they had a M Edition Z4 Coupe idling with the hood up. I peaked in the engine bay and saw the Castrol 10W-60 recommended sticker. I heard they used that oil but was impressed to see such in thing in person. Oh the beastly cars I could get if I were rich!

If someone knows the story behind their decision to use this oil in the M engines, I'd like to hear it. I've heard bits and pieces (of engine failures) but that's all. I'd be interested to hear if their "fix", this thick oil, has resulted in lessening the instances of engine failures.

Thanks.

 

[Craig in Canada]

I thought this was part of their solution to a number of S54 engines (E46 M3) with spun bearings. I believe they also lowered the redline a couple hundred RPM and a few other things. The last of the M coupes, MZ4s etc.. use the same power plant.

 

[JAG]

Thank you. So it was a bearing issue and not valvetrain. Interesting.

 

[jaj]

This is one of those stories that deserves a better tale, but actually doesn't have one.

It began in 1999, when BMW released the E39 M5 to the world outside North America. The "ONLY" specified oil was either Castrol RS 10w-60 or the equivalent Veedol Synthetic Z 10w-60 (both BP subsidiaries, presumably the two oils were actually the same product). In 2000, the car arrived in North America and six months into production the oil was re-specified from TWS-only to BMW "High Performance Synthetic Oil". In the rest of the world HPSO was called "LL-98". HPSO was 5w-30 and LL-98 was mostly xw-40. 10w-60 had disappeared from the radar.

Then the E46 M3 arrived in 2000 as a 2001 model. HPSO was specified as the lubricant. Then things started going wrong - the rod bearings started failing and blowing engines up. Unceremoniously, HPSO was replaced with the new oil product "TWS Motorsport" from BMW, which was actually the same oil as RS 10w-60 before Castrol reformulated the RS products for retail distribution. TWS is just RS from the "API SJ" era.

In my imagination there was there was a brief conversation between the "M Division" engineers for the E46 M3 and the BMW AG management. The "AG" division guys said "M3 engines are failing" and the "M" division guys said "we told you that would happen with that thin engine oil". After that, ALL "M" engines were switched to use TWS exclusively, although the E39 M5 continued to use either TWS or HPSO/LL98 or LL01 oil until the engine ended production in 2003.

Later in life, it turned out that the M3 engines were failing because of defective bearings delivered by the manufacturer - the failures were not oil related, and those that kept records said that failure rates were not statistically different between HPSO and TWS. But the M engineers' point had been made and to this day all new "M" engines are produced with TWS in them and they stay that way for life.

It would make a great movie...

Cheers
JJ

 

[JAG]

Thank you. That's just what I was looking to hear. That would make a great movie.

 

[Dr. T]

The 10-60 synth. is OTC synthetic oil is most of europe. Found everywhere from grocery stores to corner shops. No big deal. It is a 'racing' synth. grade.

Pedestrian cars get 5-40/50 synth. Cheapo. cars 15-40 dino.

 

[tripleM]

Is there any alternative equivalent to the BMW 10W-60 RS in the states?

 

[Gene K]

Closest thing in a Commmonly available 10W-60 oil would be 15W-50 Mobil 1 or Castrol Syntec 5W-50. There are some other 10W-60 Oils available but they are in the boutique brands.

 

[windnsea00]

Lubro Moly sells a 10w60, I see it at my local euro parts store. MZ4's aren't too expensive actually...start at $50k so you should be able to pick up a year to two old one in the lower $40k range sometime in `08. The average cost of a new car purchase in the US is just a tad under $30k to put it in perspective.