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Discussion Starter #1 (Edited)
Hi,

I am a bit concerned, I went to a independant bmw specialist and he did my oil change with semi-syntetic motul 15w50 oil. I always used castrol tws 10w60 in my engine.

He told me the tws I was using, was useless in my engine because it was designed for the latests bmw m power engines. He told me the motul oil was better suited for my car and that i was paying to much for the castrol tws. My concern is the change from synthetic to semi synthetic... Am I doing something wrong?
 

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A semi synthetic has a small percentage of Group 3 base oil in it - 10-20% IIRC.

Full synthetics comprise 100% Group 3 or Group 4 base oil. TWS is formulated with Group 4 (PAO).

TWS cannot even be compared to a Motul Semi Synthetic, the former is way way better in its lubrication properties. By way of example, normal group 1 base oil costs $1300per Ton. A group 3 costs about $2300per ton and a group 4 about $ 3500per ton. If oil companies could get the same lubrication properties with group 1s, believe me we would .

You dealer obviously has the Motul in stock - bulk or in 210L drums. He naturally wants to sell it to you.
 

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Discussion Starter #3
A semi synthetic has a small percentage of Group 3 base oil in it - 10-20% IIRC.

Full synthetics comprise 100% Group 3 or Group 4 base oil. TWS is formulated with Group 4 (PAO).

TWS cannot even be compared to a Motul Semi Synthetic, the former is way way better in its lubrication properties. By way of example, normal group 1 base oil costs $1300per Ton. A group 3 costs about $2300per ton and a group 4 about $ 3500per ton. If oil companies could get the same lubrication properties with group 1s, believe me we would .

You dealer obviously has the Motul in stock - bulk or in 210L drums. He naturally wants to sell it to you.
Ok, thanks!.. but am I doing any wrong to the engine by running with that oil or should I switch to TWS again?
 

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Look if it were me, I'd replace it as soon as convenient to do so.

Providing you are not driving your car hard, running up to the red line, or tracking your car, its probably okay. That said, that not how one drives a //M car is it?
 

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Fantastic response .......For a minute , I thought this was going to turn into another one of those inane oil threads .

It's suprising how many mechanics will base their advice on what suits their own purposes ........ thank god he didn't have a barrel of Planet oil in house !
 

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I have been advised by someone who really knows their stuff that they have seen accelerated wear in S38 engines with 10w60 oil. BMW recommend 10w40 or 15w50 oils for this engine, I would stick to that.
 

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Discussion Starter #7
I have been advised by someone who really knows their stuff that they have seen accelerated wear in S38 engines with 10w60 oil. BMW recommend 10w40 or 15w50 oils for this engine, I would stick to that.
even if the car used synthetic oil in the past?
 

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I would still use fully synthetic oil for the reasons stated by AfricaOffroad but would avoid using 10w60 and stick to recommended ranges.
 

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I have been advised by someone who really knows their stuff that they have seen accelerated wear in S38 engines with 10w60 oil. BMW recommend 10w40 or 15w50 oils for this engine, I would stick to that.
Was that Raymond with the excessive cam lobe wear issue? If so, I suspect this relates more to the fact that occasional use allows the top end and oil channels to fully drain. On start up, top end could be a little oil starved for a few seconds.

If I lived in a cold climate, UK, Canada etc I'd definitely run a 0W?? (30 or 40), not a 15W. But it would be full synthetic (Group 4 based first choice, although 3 is also good stuff)
 

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IIRC it was one of the BMW Motorsport division guys in Germany that recommended the use of Castrol Edge / TWS 10W60 specifically for the S38 engine .

Do you mind me asking who suggested otherwise to you ?

We need to consider that oil technology has moved on vastly from 1995 when the last of these S38 engines were put into E34 M5s and the owner's manuals produced .
 

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IIRC it was one of the BMW Motorsport division guys in Germany that recommended the use of Castrol Edge / TWS 10W60 specifically for the S38 engine .

Do you mind me asking who suggested otherwise to you ?

We need to consider that oil technology has moved on vastly from 1995 when the last of these S38 engines were put into E34 M5s and the owner's manuals produced .
Darren Farrell. Although this was in relation to road use. He recommended 10w40 or 15w50 for track/hard road use.
 

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I can't see any reason why TWS 10-60 would cause accelerated wear in S38 engines. I'm sticking to it, especially after the guy from M-division recommended it for extra protection of the bearings ,which has been a weak point of some S engines. I doubt there are many better oils out there for S38 engine.
 

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Forget the brand names. Its not the issue.
Synthetic or semi-synthetic is not the issue.
Castrol make great oils. The viscosity is the problem.
Please refer to your vehicles handbook.

Back in the mid 1990's Ford motor companies franchised dealers started selling
Mobil 1 in 0w/40 instead of its previous iteration 15w/50 = recommended for
Cosworth FI engines.
Ford & its supply chain said its "Approved"
This new viscosity of oil was not developed or tested for the Cosworth FI engine.

Many engine issues were reported from excessive oil consumption
through to worn cylinder heads, bores & blown engines ( pre-ignition caused
many destroyed engines that still ran a closed loop crank recirculation breather system )
The RSOC took it to FOMOCO, as did some of the racing & rally teams that were partners to Ford.
The oil you know currently as mobil 1 rally was the oil hastily restocked.
Its viscosity grade..15w/50

That very same Mobil 0w/40 oil viscosity forced a change in ring pack & piston to bore
tolerances on the last 3 yrs production of Aston Martins V8 "Vcar" production. :1zhelp:

Personally...
Please keep using the incorrect viscosity of oil for these engines.:applause:
The more of you that use 10w/60, the better it will be for BMW who
supply powertrain parts for these vehicles in increasingly limited batch runs &
those who can fit them..properly.

Why is it that 10w or 15w /40 oil has served countless hard driven high mileage S38 engines with no obvious damage ?
Yet those running 10w/60 for the last 4 yrs & much less have excessive camshaft pitting & obvious
considerable carbon depsosits everywhere that is visible ?
It must be coincidence !:3:

Current high performance engines, developed in parallel with the manufacturers of those lubricants give us
the extended service intervals.
That is also a function of better manufacturing process & surface treatment of the moving parts.
Oil technology has moved on.
Mass production engines & emissions technology has moved on.
The S38 is right back there isn the 1980's.

Please look out for posts by a new member who is currently registering.
His ID is "Oilman" ( see Dan Kellys link to Ivans post).
His past technical contributions to other messageboards have been first class.

Cheers
Farrell
 

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Forget the brand names. Its not the issue.
Synthetic or semi-synthetic is not the issue.
Castrol make great oils. The viscosity is the problem.
Please refer to your vehicles handbook.


Personally...
Please keep using the incorrect viscosity of oil for these engines.:applause:
The more of you that use 10w/60, the better it will be for BMW who
supply powertrain parts for these vehicles in increasingly limited batch runs &
those who can fit them..properly.

Why is it that 10w or 15w /40 oil has served countless hard driven high mileage S38 engines with no obvious damage ?
Yet those running 10w/60 for the last 4 yrs & much less have excessive camshaft pitting & obvious
considerable carbon depsosits everywhere that is visible ?
It must be coincidence !:3:

Current high performance engines, developed in parallel with the manufacturers of those lubricants give us
the extended service intervals.
That is also a function of better manufacturing process & surface treatment of the moving parts.
Oil technology has moved on.
Mass production engines & emissions technology has moved on.
The S38 is right back there isn the 1980's.

Please look out for posts by a new member who is currently registering.
His ID is "Oilman" ( see Dan Kellys link to Ivans post).
His past technical contributions to other messageboards have been first class.

Cheers
Farrell
Darren ,

Whilst viscosity is obviously an issue , it is not the only issue .

Quote from the oilman : ' if you drive a high performance or modified car, and you intend to keep it for several years, and maybe do the odd “track day” or “1/4 mile”, then you need a genuine Ester/PAO (Poly Alpha Olefin) synthetic oil. <?XML:NAMESPACE PREFIX = O /><O:p></O:p>
<O:p> </O:p>
These oils cost more money to buy, because they cost a lot more money to make.<O:p></O:p>
<O:p> </O:p>
Very simply, you always get what you pay for, cheap oils contain cheap ingredients, what did you expect! '

This would suggest that viscosity is not the only problem !

May I ask , exactly which powertrain parts that you have personally seen fail as a result of running 10w60 ?

You mention the owner's handbook which suggests 15w40 or 15w50 and yet the oilman recommends 5w40 fully synthetic .......Why has he deviated from the handbook ?

Darren , I respect your knowledge and I also respect your experience .....however , I also remember you having no problem whatsoever with adding a bottle of my Castrol Edge 10w60 to your S38 on our visit to Bruntingthorpe and hope that whatever other oil was floating about in the sump was sufficient to lessen the negative impact that this addition may have caused !
 

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So there's no problem with a fully synthetic 10w40 then :dunno: or do we need the oil companies to produce a 12.5w45 to suit everyone :hihi:

I just buy the cheapest 'good' synthetic I can find at the time - it just meant that this time it was 25L of Silkolene Pro-S (at £30/5L).

If I know I can 'get away' with using 'cheaper' 10w40 Magnatec, GLX, GTX, Chevron and the like (Chevron's about £25 for 25L at Costco, but don't know what spec it it) and can save 50-75% on regular oil bills then it means over 20,000 miles I'll save £130-£190 a year (assuming 3 interim oil changes @ 6 litres and top-ups @ 1L/1500 miles = 33 litres @ £3.50/litre).
 

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.....so this has ultimately reverted to one of the dreaded oil threads.:1zhelp:

I guess since this is an issue very close to our hearts, and engines, a resolution will be very hard to come by. :7:

So what do we do ?

There is sooo much info. on which oil to use and which not to use that one can burst a blood vessel thinking of which way to go.

I initially used Castrol Magnatec 10w/40 but got a huge consignment of TWS Motorsport 10w/60. Changed the oil a couple of weeks ago and the engine seems to be running much smoother.

My thinking was based on the research I did on site here and the fact that we have high temps. all year round.

On some of our long trips while doing 240km/h for over 300km's we see temps. over 100F with extremely high humidity....:3:.

I sure as hell don't want to see premature cam wear on my engine given these operating conditions......but what is the correct way to go :dunno: ?
 

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David
This is the full thread from which you are quoting :
http://bbs.scoobynet.com/general-technical-10/608314-oil-you-get-what-you-pay.html
Your grasp of oil technology is simply quoting what another
Engineer has quoted but this is more in context on forced induction engines in the main
where lubrication duties have vastly greater temp / pressure criteria than that
found on a large n/a engine with a very efficient engine oil cooler fitted as std.

Thats why I use Mobil one 15w/50 synthetic on my Skyline.
It's duty cycling means constant exposure to several hundred degrees Celcius within the
intermediate housing of the turbocharger.
In extremes, the Turbocharger can reach 1000 Deg C
All that with high pressure oil feed to the turbine shaft bearings, you need
the best chemical formulation when bulk oil temps exceed 140 Deg C
Its resistance to breaking down under these much more extreme conditions make
it worth paying for.
With the added security that its an oil that is proven to work in a forced induction vehicle using the
correct viscosity.

May I ask what the highest bulk oil temperature you have measured on any of the
E34 M5 's you have owned ?

I would suggest that whilst viscosity is not the only issue , in context of the application for S38
where oil bulk oil temp rarely, if ever exceeds 110C or around 230F, the engines do not need anything
remotely exotic.
The "Planet oils" I use are rated far beyond this temperature.

The S38 application :
The vehicle in B36 guise was a world vehicle in 1988.
In B38 circa 1991,it was a mainly European offering due to pass-by noise & emissions
In all cases, it was tested on Cold crank test, Autobahn signoff, Altitude soak @ Grossglockner &
as you have quoted, many thousands of Kms at the Nordschliefe.
All this with Mineral oils @ an average of 6k mile service intervals.
So then, whats changed please ?

Oilman has recommended 5w/40 for colder climates & winter use where more
efficient cold crank can utilise the thinner when cold oil.
He has just been approved as member & I am sure he will be happy to answer
specifics.

David
I have seen no actual failure of the valvetrain parts in this application...yet.
What I can say without doubt is the that all the cars I have seen
running 10w/60 have bad pitting of camshafts.
No exceptions.
These engines as exmained have as little as 90k miles on them.
From past experience, it has been documented that when pitting gets bad enough,]
the surface hardening of the cam no longer has
the integrity.
The compression, shear & turning forces concentrate on the damaged areas.
These areas being softer are more likely to fracture over time with
micro-cracking emanating from the damaged areas.
When a camshaft lobe disintegrates, its usually fatal for the engine.
No big mystery.
Same with crankshaft bearing shells in that once you are through the hardened land,
then,wear through the soft shell & potential brg shell being spun out by the crank, a likely conclusion.

The 10w/60 oil you lent me was drained the next day as you know.
Thankyou.

My own engine has no pitting or visible damage of any kind @ 180 plus k miles.
All run on 10w or 15w /40 "Planet oil" for the last 8 years.
A highly stressed ,fragile, about to go bang 3.8zzzzz
Wow, who would have thought it.
 

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i was under the impression that infrequent use was a cause of the cam pitting? My m5 has a small amount of pitting (compared to pitcures i've seen posted here), as far as i can see thru the oil cap hole, and has used 20w50 Kendal GT1 or Castrol GTX 10w40 for most of its life (up to about 145k miles). I put TWS in, as that's what i had in my cabinet for my e39, when i last changed it.
Personally, i just want to use what is best for the engine, be it cheap or exotic, i wont discriminate!
 

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Yes Mike
I believe intermittant use could be a factor.
However, the cars I have seen were users apart from one.
Again, I am not with the ownersouich
At the same time, my own car has seen intermittant use for the last 2 years.
I am not seeing the wear issues.
I am not an oil Engineer so I would prefer them to have a definative say.
I can only convey personal long term usage, past experience & what I am
finding now & log the findings @ mileage first seen.
 
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