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I have never ever seen S38-B35/M88 84mm, to have baring issues ever also the 3.6 86mm stroke.
Me neither; when I rebuild my M88/3 engine im 2009, the old 4/85 marked bearings showed no signs of wear. And the UOA's of a friends S38B36 with 310km's show no indication of bearing wear what so ever as well.

The amount of lead in Ficelle's M88/3 certainly is abnormal and I also concur with your advice. The sooner the rod-bearings are inspected the better because it appears as if the second layer may be through and once that happens, the crankshaft will be affected as well. And in if that is the case, the crankshaft needs to be machined to first undersize, which is an engine-out job...... which is nothing more or less then a (bottom-end) engine rebuild.

This certainly might be the result of using low-viscosity engine oil, e.g. a generic 5W30 with a lo low HTHS or an extended service interval with low base-grade oil (5W or lower) that has seen a break-down of the polymer-chains that stabilizes the temperature behavior. Once that happens, an engine oil will break down to ist base-grade, resulting in a much lower viscosity at operating temperature. But this also results in a reduction of the oil-pressure to below the minimum threshold (that should have been observed), especially at lower engine speeds.

Replacing the engine oil does resolve this phenomenon, but does not resolve its result .... excessive bearing wear. Chances are that the situation resolves with replacement of the rod-bearings, especially when the engine does not make any noises, but immediate action is required to prevent further damage.
 

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This is a great technical thread. I've recently had an oil conversation with a mate and it's prompted me to chime in.

Of all the short-list oils Raymond has mentioned, only Motul 300v 15W50 is easily available here in Australia. Though it is easily available, it is also somewhere around $100 / 4L.

I decided to try approach the oil topic with budget in mind as well. Given that the venerable old S38 likes frequent oil changes and there are many high-mileage examples out there in fantastic conditions which undoubtedly spent many of those miles on plain old mineral oil... there's no reason why you "have" to use a fully synthetic group 4 oil for adequate protection.

I stumbled onto a semi-synth shell product, HX7K 15W-50 "high mileage". it is marketed as an oil for engines >100k km and has "extra anti-wear additives" according to the bottle. this oil interested me because:
firstly it is 15w50 which is explicitly mentioned as a viscosity in the user manual.
secondly, it meets ACEA A3 which means it is > 3.5 mPa.s HTHS.
thirdly, it does not meet SM spec, it is an SL oil which means it does not need the dramatic reduction in ZDDP.

I decided to ring Shell tech support and ask about it and the service rep informed me that the Zinc level is 1232 ppm and Phosphorous 1114 - so nice and high for our flat cam follower engine.
she couldn't tell me the exact HTHS spec (which i thought was weird) but confirmed that it is above 3.5.

So it meets the very logical viscosity, film strength and ZDDP requirements Raymond set for himself and his S38.

Anyway, this oil costs about $30 / 5L here so I can get 3 oil changes done before I'm getting close to the cost of 300V.

I don't have any VOAs or UOAs to contribute but I thought i'd chime in with this info for the Aussies :)
 

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I stumbled onto a semi-synth shell product, HX7K 15W-50 "high mileage". it is marketed as an oil for engines >100k km and has "extra anti-wear additives" according to the bottle. this oil interested me because:
firstly it is 15w50 which is explicitly mentioned as a viscosity in the user manual.
secondly, it meets ACEA A3 which means it is > 3.5 mPa.s HTHS.
thirdly, it does not meet SM spec, it is an SL oil which means it does not need the dramatic reduction in ZDDP.

I don't have any VOAs or UOAs to contribute but I thought i'd chime in with this info for the Aussies :)
:thumbsup:

You have perfectly understood the essence of my epic and I couldn't agree more, also with your opinion that the S38 doesn't necesarilly requires 'expensive' synthetic oils and can do with a good quality mineral of basegroup II as well.

I do encourage you to have a sample analyzed by Blackstone after you have to change again and share your observations as well.

But again, thanks :cheers:.
 

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Hi guys,

I was out for my job, so couldn't reply earlier...
my M6 is mine since 2001, and when I bought it she had 82000km on the clock.
she 's now 141m km, and with me always had 15W50 oil.

I have to agree with you this high lead value afraid me a lot...but engine is so smooth and running so well...I always wait the oil temp to get to 75°C to go upper than 2000 rev/min, and never go more than 6000.
I cannot imagine bearing getting "dead" after only 140000km of normal use... can it come from oil ?

anyway I'll make another analysis next year when I'll have done more or less 2000km..
:dunno:
 

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I have read that if a car sits for a long period in dirty oil then it can eat away at lead bearings and substantively reduce their life. This, I believe, is one of the main reasons for the common advice to store your car with clean oil. I agree with Raymond - do another analysis soon and if in doubt have the bearings replaced - I think they can be accessed from underneath, and it isnt that big of a job.

Hi guys,

I was out for my job, so couldn't reply earlier...
my M6 is mine since 2001, and when I bought it she had 82000km on the clock.
she 's now 141m km, and with me always had 15W50 oil.

I have to agree with you this high lead value afraid me a lot...but engine is so smooth and running so well...I always wait the oil temp to get to 75°C to go upper than 2000 rev/min, and never go more than 6000.
I cannot imagine bearing getting "dead" after only 140000km of normal use... can it come from oil ?

anyway I'll make another analysis next year when I'll have done more or less 2000km..
:dunno:
 

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Hi Matt,

that can be a possibility...
sometimes my M6 stays 3 or 4 months without any drive.
So it can came from the first 10 or 20 second without the appropriate oil pressure... ?:dunno:
anyway I'll check in next 2000 km...and we'll see.
At the BMW club France there is more or less 10 M88 and S114, all have more mileage than me, and all theses engine were never opened.
never heard also in france about bearings trouble in S14 and M88...

BUT: If the second analysis confirm the first one, then I'll ask my mechanics to do the change :dunno:
 

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sometimes my M6 stays 3 or 4 months without any drive.
So it can came from the first 10 or 20 second without the appropriate oil pressure... ?:dunno::
10-20sec with the oil-pressure light on means that engine oil pressure is less than 0,5bar!!! at 900RPM idle, this equates to 150 to 300 engine revolutions!!!!! This can go well for a long time for as long as the first layers of the bearings are still OK, but at some point wear will increase exponentially.

The oil pressure light from my M88/3 dissolves within one second, even after a few months of storage! But even then, I disable ignition and fuel pump to build-up oil pressure to avoid high bearing pressures in the third stroke!

I would advise definetelly not to leave this unattended.
 

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10-20sec with the oil-pressure light on means that engine oil pressure is less than 0,5bar!!! at 900RPM idle, this equates to 150 to 300 engine revolutions!!!!! This can go well for a long time for as long as the first layers of the bearings are still OK, but at some point wear will increase exponentially.
Hi raymond, you must think this guy is silly !!!! :biggrin:
yes 10 seconds sounds silly:eek7: !

I said 10 / 20 seconds machinally, but actually I don't really know, after reflexion it is surely closer to 1 or 2 seconds.

I did'nt watch it really.
I do have a temp and oil pressure indicator like the one on the photo ( this photo is from a 635csi )



pressure rapidly ( but what is behind this word rapidly ??? ) goes up to to 5 bars when engine is cold at 900rpm; and 2/2,2 when at 90°c.
I'll check the real time to shut the pressure light next time I'll start the engine! surely this weekend.

PS: never tried to make engine do some revolution before putting on ignition.
that sounds great for long storage period...:)
 

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Hi raymond,
I checked this weekend...
between 2 and 3 seconds before the light stops, and the pressure indicators start to rise up to 5...
;-)
 

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The last sample of TWS that was run on GV44730 (M54B30 engine) and sub sequentially tested by Blackstone proves that Castrol continues to keep the weight of ZDDP at absolute minimum values, presumably to meet EPA requirements to guarantee the lifetime of the emission control systems throughout the cars life. In fact, the tested sample contains only 685ppm of Phosphor, which is an all-time low since m5board members started sharing UOA/VOA reports [#1].

Nevertheless, except for copper, the elements that determine engine wear is much lower than the universal averages for this type of engine (@10300km) and also considerably lower than GV44730’s the previous lab report of July 2013. Given the fact that GV44730 suffered two major incidents last year, namely (1) engine overheat as a result of an exploded coolant bleeder screw and (2) failure of the non-return valve in the oil-filter assembly resulting in longer oil-pressure build-up times, it is remarkable to see such low results on (1) the wear-related elements and (2) an absolute absence of antifreeze and water in the oil.

Bu what is the relevance of this result for our M88/S38/S14 engines? At least two things. This lab report provides new input to the ZDDP trending data since 2003/2004 and a confirmation that the lubrication performance is maintained far longer than the protection performance.

According to an Email that I received from the Castrol technical helpdesk in July 2012, Castrol specifies the content of Zn for its Edge Professional TWS to be within 960ppm and 1090ppm. For this sample, Blackstone measured 815ppm for Zn (905ppm for the previous sample), both of which do not meet the manufacturers claim from July 2012 for this oil-type. But let’s review if this still is considered a problem? The problem is that without accurate data / models about the rate of depletion of ZDDP for an S38/M88/S14 engine, it is difficult to assess the useful life of ZDDP. However some assumptions can be made:

1: The decay of the remaining active compound of ZDDP can be linearized
2: After 10k km, almost all of the active ZDDP has decayed into its basic elements (Zn & P).

In 2000, BMW did approve Castrol TWS for use with the S38/M88/S14 engines [2]. At that time, Castrol specified TWS for having 1000ppm on Phosphor [3]. Since the S38 has an ‘intelligent’ service interval indicator to advise owners that an oil change or inspection is pending, owners generally rely on that indicator for planning their service scheme. The service indicator generally measures parameters like the number of engine starts, mileage and engine coolant temperature cycles to determine whether the service interval should be reduced from the 7500km maximum as suggested by BMW AG. However, at the time of the S38/M88/S14 development, ZDDP requirements were determined solely by engine requirements (protection against scuffing metal to metal contact under high pressure and high load) so it is unlikely that the service indicator takes the depletion of ZDDP into account or when it does, only as a simple modelling algorithm based on the minimum SAE requirements of an API SF grade engine oil .

It is imperative to realize that when using low ZDDP engine oils for S38/M88/S14 engines, the service life should be derated even further. Based on the assumptions and BMW service interval of no more than 7500km for these engines, one might argue that whilst maintaining for a 25% safety margin, the rate of decay is 100ppm of Phosphor for every 1000km.

If one extrapolates that to the measured amount of Phosphor in the last tested sample of Edge Professional TWS, the point where the active compound of ZDDP reaches zero is 6850km! This is 10% short of the recommended oil exchange interval of 7500km, let alone adhering to a safety margin of 25% that would derate the maximum service life of Edge Professional even further to no more than 5200km! However, since most S38/M88/S14 engines are used ‘appropriately’, it is advisable to derate the service life of the engine oil even further even when TBN measurements will prove that the oil is still far from the point to become abrasive (TBN <1).

With a specified amount of 1300ppm on phosphor, the zero point of Mobil1 Extended Life 10W60 will occur no less than 13000km, add the safety margin of 25% and a useful service life of 9500km can be achieved, which is well above the 7500km exchange interval from BMW. Granted, there are not yet enough UOA reports of this oil available, but as TBN is on the same level as TWS, lubrication performance of Mobil1 EL 10W60 is about the same so 7500km with spirited use and sustained high speed driving on the autobahn should not be a problem.


References:
[1] Results of a virgin oil sample as shared by m5board member ‘DavidS’ on the E39 M5 section in September 2005.
[2] SBS 8.0 "Special oils" BMW AG - TIS 30.12.2004 08:30 Issue status (02/2004)
[3] Technical Datasheet Castrol TWS Motorsport (27. April 2000/mp - DCV18335/04-2000/001)
 

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Great post Raymond.

I wonder about the assumption of linear decay in oil. You have many more data points than I, but when checking oil levels over the years my perception has been that the rate of use increases as the oil gets old. Indeed, I often take that as a prompt to change it.

Do you think its plausible that the rate of ZDDP decay could actually be a curve ?
 

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I wonder about the assumption of linear decay in oil. You have many more data points than I, but when checking oil levels over the years my perception has been that the rate of use increases as the oil gets old. Indeed, I often take that as a prompt to change it.
I notice this so much more with the M5 than any car I've had before... at the same time as the oil starts to "darken" / get dirty - it starts to use a little of it...

whereas, when the oil looks relatively clean (as in, same colour as in the bottle), it doesn't seem to use any at all.

and I thought I was imagining this ;-)
 

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I wonder about the assumption of linear decay in oil. You have many more data points than I, but when checking oil levels over the years my perception has been that the rate of use increases as the oil gets old. Indeed, I often take that as a prompt to change it.
I would like to place a few fences here. First, any engine uses oil. The rate of which depends on (1) internal clearances, (2) type of usage and (3) the (remaining) quality of the engine oil.

AFAIK, oil does not contain elements that dissolve when coming in contact with oxygen (O2). Oxidation for engine oil, just defines a process in which oil molecules are converted to insoluble (e.g. carbon) due to a combustion process (that always includes oxygen). Since this is temperature related, I would say that usage is the main limiting factor in this process and to a much lesser extent, the shell life. Now let’s revert to the following phrase:

“……but when checking oil levels over the years my perception has been that the rate of use increases as the oil gets old”
This merely focusses on the ability of the engine oil to absorb contaminants (e.g. fuel, condensation etcetera). The fact that an oil turns into black does not necessarily mean that an oil has reached its End Of Life. It merely indicates that the detergents in the engine oil do their work. This ability (detergency) of the engine oil usually is specified by its Total Base Number (TBN). The higher the TBN, the better the oil is able to absorb contaminants.

I have observed that when running on TWS, my M54B30 and S38B36 as well as a friend’s S38B36 start to use oil shortly after 6000km on the oil. Another observation from an acquaintance who is running an original Hartge 323i RS, that the oil pressure of TWS drops slowly but gradually well before reaching that point. Given the fact that most oil pumps are constructed for a constant volume output, this can only be the result of a reduction of the oils thickness, which indicates to a premature breakdown of the polymer additives that are used for achieving multi-grade abilities to a single grade base-oil.

It is interesting to plot a graph of the TBN as function of the covered distance, in fact I did plot this for UOA’s that I have available, but it is impossible to compare apples to apples here, some cars already bottomed out on TBN after reaching 6000km. This does not reflect my own experience as my own reports show that TWS has a remainder TBN of 5,7 after 6109km and 3,3 after 9000km and 1,3 after 11020km. This is still sufficient for the oil to absorb contaminations / condensation, fuel dilution.

Do you think its plausible that the rate of ZDDP decay could actually be a curve ?
IMHO, the rate of decay of ZDDP is independent of the rate of decay of the oil itself (TBN). The Phosphor element adds a positive polarity to the Zinc element due to which it is attracted by metal parts creating a disposable protective layer as first line of defense against scuffing metal to metal contact. It is a fact that ZDDP depletes as a function of usage. There are external studies that state that depending on engine (design) and type of usage, ZDDP decays within 2000-4000miles. Now I must admit that these studies were limited to engine designs with solid-lifters as used in amongst others classic engine designs such as the big-and small block V8’s from GM. These combine a central placed camshaft that operate their cams using solid lifters and usually very stiff springs.

It is a fact that cam-lobe wear has been observed in other car scenes, the classic US muscle cars are a good example and there are niche-market players (e.g. Bradd Penn) that offer high ZDDP (mineral) engine oils. In fact, the debate whether or not to ZDDP has long since been played and fought, not least because oil-companies are forced to lower ZDDP to address environmental concerns. In fact Bob Olree at all designed a test (Sequence IIIG) to prove that engine designs with solid lifters are compatible with low ZDDP engine oils, yet they used a low-performance engine that was at hand and operated it at a continuous 3800RPM, which is hardly about halve of what our S38’s can achieve.

The question whether or not to ZDDP, is not so much about performance claims of oil manufacturers. It is about trust in relying on their testing methods and performance claims. I fully understand that oil manufacturers are not capable to test twenty to thirty year old engine designs for compatibility, leaving the choice open to the discretion of the owner. As such, we simply present and discuss the facts in this thread.

I do not doubt that ZDDP decays, but whether this curve is linear or not-linear is something that I do not know, hence why I assumed to simplicity whilst allowing for a 25% de-rating factor to limit the dynamic error. This is based on the following contemplations; (1) At the Begin Of Life, the ZDDP additive is sufficient and any non-linearity in the decaying curve is not really of interest, (2) An SAE paper states that there is direct relation between (lifter foot) pressure and ZDDP, so it is easy to reestablish the link to cam-lobe pressure for (D)OHC designs, at least conclude that the same process applies. However, it is difficult to be specific other than empirically retrieved data from my own observations, based on which I made the assumptions in the previous post, but even when incorrect, these place a marker for further discussion and reference whilst informing owners so they can make their own contemplations/decisions.

In any case; long oil-change service intervals are detrimental to the longevity of your engine!
 

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I have observed that when running on TWS, my M54B30 and S38B36 as well as a friend’s S38B36 start to use oil shortly after 6000km on the oil.
wow! I never keep my engine oil longer than 5000k before a change, and with new oil before any track day use, this probably falls to 1500km average for me in the last 30 months.

In any case; long oil-change service intervals are detrimental to the longevity of your engine!
I guess I should be ok then :)


Thanks for the posting Raymond, I kept up most of the way with your great explanation - and oil + chemistry is not my area of knowledge!
 

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I notice this so much more with the M5 than any car I've had before... at the same time as the oil starts to "darken" / get dirty - it starts to use a little of it...

whereas, when the oil looks relatively clean (as in, same colour as in the bottle), it doesn't seem to use any at all.

and I thought I was imagining this ;-)
I have noticed this as well. I also not different brands of oil are consumed at very different rates.
For example, i was running Redline 15w50 in both of my s38's. It has a good amount of zddp and seems to be a good oil. I initially had to top off some oil after 1000 miles, then again about 700 miles later, then again 4-500 miles later. etc. Eventually it seemed like i was adding some oil (a half L or so) with every fuel fill up. I ran this oil for about 6000 miles.

I didn't remember this fairly high level of oil consumption when i was using TWS, so next change, i used TWS and a zddp additive. I've gone 3000 miles with no oil additions.
 

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it's funny you mention different behaviours of different brands....

I'm using Mobil 1 extended life (10 60) - and I've noticed that the initial period of "non use" of oil, seems to be a fair while longer (ie, higher KM), but, once it starts using some, it gets on with it, and uses at least 250ml - 400ml most top-ups'

With silkolene / fuchs titan pro R it used a lot less each top up, but, I didn't like the oil compared to Mobil1 (wont repeat comments I made elsewhere).

Nowadays I tend to only top up twice after first seeing some use before changing the oil (I always have the next "service pack" /box of consumables/ ready to go in my shed anyway).
 

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Look what arrived today:

20140802_143840 by MattH3764, on Flickr

My plan is to run the Mobil in the non cat E30 M3, and the Fuchs in my new E34 M5. I've been running the Fuchs in GE00022 for the last few months and have been really happy with it - so if Jamie is right that the Mobil is better then I can't wait to try that. When I've done enough miles I will post analysis of the Fuchs such that we can observe the ZDDP content.
 
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