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      05-12-2013, 07:29 PM   #1
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Drives: '14 335i M sport
Join Date: Oct 2008
Location: San Diego, CA

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What's In Our Castrol 10w60 TWS

I'm relatively new to this forum and don't how many of you are into doing used oil analyses or are interested in lube topics, but thought i'd go ahead and post a recent virgin oil analysis of the oil spec'd by BMW for the M3. There's a lot in the formulation of an oil that won't show up in a voa, but it is useful in interpreting used oil analyses, if you do those.

I've included a voa of TWS that I did in 2009. The 2009 voa was done by Blackstone labs, while the 2013 voa was done by Polaris labs. FWIW I've been told by a lubricants engineer that the original TWS was an ester based oil (like Redline or some of the Motul oils) that was developed from Castrol RS 10w60, a racing synthetic. He should know since he worked for Castrol at the time and was part of the team that formulated the RS 10w60. I remember when I had a 2002 e46 M3, the 10w60 first came in bottles labelled Castrol RS 10w60. About a year after that, the label appeared as TWS 10w60.

As you can see the formulation of the present day TWS has changed.

2013 Polaris voa, 2009 Blackstone voa

aluminum 8 2
iron 1 1
silicon 7 4
titanium 47 0
moly 198 2
boron 59 109
calcium 2823 1141
phosphorous 804 641
zinc 922 796

vis 100 C 20.7 22.6
flashpoint F N.A. 460
base number 10.8 N.A.
oxidation (abs/cm) 8 N.A.
nitration (abs/cm) 4 N.A.

N.A. means that the lab did not test or report for that item.

Couple of comments:

The lab test equipment "sees" or misinterprets esters in the oil as oxidation/nitration, so the current TWS is not an ester based oil. The numbers are too low. No big deal in my estimation. It has some esters in it like most modern oils, along with a mix of other base stocks. It is probably still a true synthetic (group 4 PAO) and well up to the performance demands of a car like the M3. For comparison sake, that would be like the base stock of Pennzoil Ultra 5w40 European Formula, which is the service fill for Ferrari.

The calcium adds have increased significantly. Calcium is a detergent/dispersant, but importantly also gives the oil its basing qualities - - its ability to neutralize acids formed as by-products of combustion. The current TWS is probably much better suited to extended drains.

The anti-wear adds (titanium, moly, boron, phosphorous/zinc or zddp) have increased significantly, and the new aw add pack is much more diverse. I'm guessing but the old TWS probably relied more on the esters (esters of the castor bean?) for aw protection.

The VII pack (visosity index improver) appears to be about the same. I've always thought of TWS as a heavy 50 weight when hot (vis at 100 degrees C). 21.9 centistokes is the break point between 50 and 60 weight. With heat, load, and rpm, in time and miles it shears back to a light 50 weight, and I've seen some uoa's where it has sheared back to a heavy 40 weight. No big deal. I know of some people who use Mobil 1 0w40 in e39 M5s and e92 M3s (somewhat dicey in my opinion) and that oil very quickly shears back to a heavy 30 weight.

Hope all this is of interest. Sorry I couldn't get the columns of voa items better separated.

'14 328d, '13 M3 ZCP, '12 535i, '11 335d, '09 Z4 DINAN Stage II, '05 330i ZHP, '05 M3 ZCP, '02 M3, '91 328i, '90 535i, '88 528e, '88 M5, '87 M6, '95 Z3, 95 M3, '93 M5, '87 325e, '89 535i, '86 635i, '73 Bavaria.

Last edited by m6pwr; 05-12-2013 at 08:21 PM.