WHICH OIL FOR E39 M5??

When it comes to oil discussions it can become religious. If the purpose of this discussion is to go in circles, then Im not interested, simply because these usually end up no where. I put my money where my mouth is and build up engines and track them. I do many things that are not recommended in your owners manual that you may or may not balk at, e.g. engine break in happens in less than a few hundred km.  I rev an engine over 8000 rpm with less than 100 km on the engine.  I also drop bottom ends to check the condition of rod bearings and swap new (motorsport) ones in even though the old ones optically apear in very good condition. So I am not driving the car and wondering what is going on in the bottom end without any sort of feedback.

On TWS:  it is a polar oil. AFAIK, only ester oils are polar.  It is a mistake to read too much into the "60" part of the 10w-60 designation.  This oil is NOT a 60 weight oil. It is based on a 10 weight oil. It just BEHAVES at 100C like a 60W oil.  This is key to understand.

So, you read a bit of physics and think: oh it is a 60 viscosity oil and therefore there is more internal molecular friction which must raise the oil temperature.  It doesnt work like that, nor is this seen in practice. You may trust me when I say that the engine itself under whatever operating conditions has far more effect on the oil temperature than the molecular friction in the oil!  In fact, if your engine is running too high oil temperature under track conditions, there is no oil that you can simply put it in it to lower the engine temperature any significant amount. You need hardware modifications to accomplish this. Im assuming a healthy engine, if you are getting metal to metal contact, then it is a non issue and you will not be driving for long under track conditions.

I would be concerned to run an engine over 120C on the track for sustained periods.  BMW Motorsport says that 125C is MAXIMUM engine oil temperature. Oil break down is obviously much higher than this temperature.  Can you get away with higher oil temp? yes you can, but the wear and potential for failure goes up.

Motorsport (racing division) does quite extensive modifications to increase cooling to lower both oil and water temperatures.  E.g. extra radiators, ducting and lower T-stat opening points (for lower water temperatures) and larger oil coolers and oil-water heat exchangers to keep oil temperature down. Oil coolers are run without bypass valves to eliminate any lag time -- they cool maximumm at all times as long as the car is moving. To get maximum power it is ideal to run the engine around 80 C water and 80-90C oil -- on a race engine. On a street engine we might rather see 90-100C oil temps as ideal. Just to make sure the oil gets hot enough to burn off things like fuel in the oil. On a race engine, the oil gets dumped, so fuel contamination in the oil is a non issue. On street engines it is enough of an issue that the ECU tries to determine (MSS62 and MSS54 ecus e.g.) the fuel content in the oil.  For similar reasons, when an engine has more blowby this is something that degrades the oil over time. When crank case gases are recirculated into the intake tract, this also causes problems with reduction of octane (by lowering it), increasing its likely hood (if significant) to knock -- therefore the ECU would retard its timing.  When you run tighter piston-wall clearances or have a better ring-wall seal (due to better rings, better run-in, or change of hone pattern) you usually get lower blowby.

My friends at the N'ring all use TWS. Does this mean this is the best oil to use? is it the only oil to use? of course not. But, it provides atleast practical experience that the oil is not bad, and this was my primary point.  If I go to the track, Im pretty sure Id follow their lead. But I also open the engine up from time to time to check things. I dont believe that there is any MAGIC involved.

As far as RS 10W-60 and hydro cracked oil -- I really have no comment. I was only trying to comment on TWS.

If you want to run a "long life" oil then go ahead, BMW approved it so there is no reason to second guess them right?

John

 

 

 

 

 

There seems to be a little confusion here (not on the recommended oils as this is stated by the BMW TIS and in handbooks, as correctly stated by Stephen B) over quality.

Castrol RS 10w-60 is a hydrocracked (highly refined mineral) oil and not of the best shear stability or quality.

Castrol TWS 10w-60 is a different formulation with higher HTHS numbers and NOACK volatility % due to its synthetic basestocks which are likely to be the minimum poly alpha olefin and at best a pao/ester blend.

The point is that neither 10w-60's are BMW LL oils and never likely to be as they don't meet BMW's criteria viscosity-wise (0w or 5w, sae 30 or 40).

Whilst it can be argued that 10w-60 is traditionally a grade for extreme use (based on the theory that shearing in use will mean an sae 60 will thin to an sae 40 over a couple of thousand miles of hard use) the old school way of thinking does not apply with modern synthetics.

Modern synthetic basestocks are incredibly thermally stable with very small amounts of VI improvers added meaning there is no where to shear back to. (see below explanation)

The biggest problem is the use of an oil that's very thick (as thick as some gear oils) which can mean more friction and heat leading to more engine wear, lower fuel consumption and a lower power output due to oil drag when it's not necessarily required.

Stepping up the viscosity from sae 30 or 40 to sae 60 is only warranted if oil temperatures are excessive (above 120degC) and then an sae 50 (proper synthetic race one) will adequately handle up to around 145degC for prolonged periods.

Granted in some models 10w-60 is required due to design but not for all applications by any means.

Why do oils lose viscosity with use?

 

Viscosity Index Improvers.

 

An oils viscosity will decrease as the engine temperature rises. Viscosity Index Improvers are added to reduce this thinning. They are a key addative in the production of multigrade oils.

 

VI Improvers are heat sensitive long chain, high molecular weight polymers that minimise the viscosity loss of the oil at high temperatures. They work like springs, coiled at low temperatures and uncoiling at high temperatures. This makes the molecules larger (at high temps) which increases internal resistance within the thinning oil. They in effect "fight back" against the viscosity loss in the oil.

 

"Shearing"

 

The long chain molecules in VI Improvers are prone to "shearing" with use which reduces their ability to prevent the oil from losing viscosity. This "shearing" occurs when shear stress ruptures the long chain molecules and converts them to shorter, lower weight molecules. The shorter, lower weight molecules offer less resistance to flow and their ability to maintain viscosity is reduced.

 

This shearing not only reduces the viscosity of the oil but can cause piston ring sticking (due to deposits), increased oil consumption and increased engine wear.

 

Like basestock quality, VI Improvers also vary in quality. As with many items the more you pay, the better the finished article and more expensive, usually synthetic oils are likely to incorporate better VI improvers. All other things being equal the less VI improver an oil contains, the better it will stay in grade by resisting viscosity loss. 

 

Which oils require more VI Improvers?

 

There are two scenarios where large amounts of these polymers are required as a rule.

 

Firstly in "wide viscosity span" multigrades. By this I mean that the difference between the lower "W" number and the higher number is large for example 5w-50 (diff 45) and 10w-60 (diff 50) are what is termed as "wide viscosity span" oils.

 

Narrow viscosity oils like 0w-30 (diff 30) or 5w-40 (diff 35) require far less VI Improvers and therefore are less prone to "shearing".

 

Secondly, mineral and hydrocracked (petroleum synthetic oils) require

more VI Improvers than proper PAO/Ester (Group IV or V) synthetic oils

as they have a higher inherent VI to begin with, this is due to

differences in the molecular straucture of the synthetic base oils

compared to mineral oils

 

It is a fact that many synthetics require significantly less VI Improver to work as a multigrade and are therefore less prone to viscosty loss by shearing.

Hope this helps,

Regards

Simon

I am aware of BMWs recommendations, and in that recommendation TWS was never EXCLUDED as an oil that might HARM the engine.

changing piston to sidewall clearance is hardly going to be a determining factor whether the oil is harmful or not. They trying to reduce blowby and oil consumption.  But, if you left TWS in there eventhough the oil consumption is down, that will not cause harm.

on race track we are generally interested in keeping oil temperature low, because too high oil temperature is bad for things like rod bearings. when these get damaged, you will see oilP fall (if you have a guage), then oil temperature will rise further and soon you will have a complete bearing failure.

I select an oil because it is good and for my intended use. I am not too religious about it though. I know a little more about engines than what is stated in the owners manual :)  but only a tiny bit.

John

 

 

Hey Guys, all my buddies at the Nuerburgring are using TWS 10-60 in their e39 M5. So are all the E46 M3 guys.

TWS is a real ester based oil (like Motul). That is also why it is a bit more expensive than other oils.

No engine is so special that it needs only 1 particular brand of oil. Check Porsches list of approve doils for new and older models e.g.    It is also more than ok to change the oil before the normal oil change interval comes up if you so desire.  Some things you do not have much ability to control (short of changing oil) -- like acid content -- for this you have oil additive packages. But somethings like fuel content in the engine oil is detected by the ECU.   I have it somewhere in my documentation for MSSxx ECUs where they specifically talk about fuel in oil detection.  Since they are trying to detect this, this should tell you what the importance is?

John

Cheers Steve

Thanks for the info. It is Damon Hill who Ive been using,
needless to say I'll be talking to them about this !!!

Sorry to go on about this guys, but I'm totally confuesd now and
a little concerned, apologies for being thick !!!

So which oil should I be using in my 2001 M5, cos my Dealer
suggest Castrol TWS 10-60 and this oil is even listed on the
BMW car Club website
www.bmwcarclubgb.co.uk/sections/mpwr/M5s/M5E39Extra.htm

Can anyone point me in the direction of the BMW bulletins
regarding the oil type (are they for public viewing) so that I can
see for myself.

Sorry to add to the dismay at BMWs seemingly endless ability to actually give a straight answer on the oil for M5s topic....

I have been very concerned about whether I had the right oil in my car since the last service (just prior to when I purchased the car) - I have a 2001 M5 - thus my thoughts are that it should have a BMW LL01 oil - like Castrol SLW 0W30.  I have discovered that it has had TWS put in it by a dealer in the NW.  They are adamant that this is correct.  I checked with BMW GB who confirmed that I was correct and that LL01 must be used.  I spoke to the dealer who were not impressed at all.

I then decided to refer back to BMW GB and spoke to cust services who informed me that whoever told me that LL01 is the right oil should NOT have told me that and had no authority to do so.  I nearly lost it there and then.  This chap was so unhelpful and said that as he wasn't allowed to talk to people like Jeff Abbott, then I certainly wouldn't be able to.....

He said he had to refer it back to the dealer - what a joke....meanwhile what I am meant to do with my car when it's got the wrong oil in it...?

I rang another dealer more local to me - and they insisted that TWS was the right oil....and that wait for it......Castrol RS 0W40 must be used on M5s up to 2000.....

I await the outcome from BMW GB.....how frustrating is this...?

Chris

I think BMW should look harder into the reasons for engine failures and they may find that Dealer incompetance is a major factor.

An oil that is too thick can cause damage long term through additional friction, heat and wear but in the short term the worst case scenario is cavitation causing oil starvation on start-up.

The vanos problems could very well be caused by temporary oil starvation as the thicker oil takes longer to circulate around the engine and oil pressures being too high at temperature.

These threads sadden me and although I'm sure there are some perfectly competant Dealers out there, unfortunately there are too many that just don't read or understand BMW's technical bulletins.

I can only say once again:

"Your handbook is an important document and is very specific about the correct viscosity oil for your car, READ IT!"

If you don't understand it, email me the relevant page and I'll do the work for you.

sales@opieoils.co.uk

Cheers

Simon

 

 

 

yea i will have to report them for that one!

over 1 liter above the max level,i did 30 miles like this!

what damage can occur from this type of stupidity?

i thought they would at least change the filter,ive now got

0w 30 with 10w 60 cocktail! no wonder bmw have to supply

new engines to there customers,i just feel sorry for those m5 owners who dont have a bmw warranty!

 

Edited by eljockvis

guess what now?

after i got home from getting the oil changed to 0-30 slx

i checked the level and it was way above the max on the dipstick,so

i had to drain 1 liter of oil in order to reach the maximum level !

how bad is that for the engine?