BMW E39 M5 Oil Debate Opinions

[captainanonymous]

Firstly, I have been trying to search on this forum, I put "BMW" in the advanced search options for subject or content, I set posts in the last 10 years and go 0 responses, and selected all forums for the search. I think something is a miss with the search surely!? Anyone any idea why?

Anyway, I gave up searching (and not getting any responses) and trawling so decided to open another thread.

This is all about the E39 M5 oil debate; 10W-60 or 5w30 (the oil recommendation was changed in March 2000 to 5w30, a BMW long life oil).

For a lot of debate and information on this topic visit:

http://www.m5board.com/vbulletin/e39-m5-e52-z8-discussion/142633-what-bmw-has-say-subject-oil.html

I currently own an E39 M5 2002 model and it's running 10W-60 Castrol EDGE currently with no real issues. The motor seems fine and does consume perhaps a litre in 3000 miles or more. I am going to be due a service soon, and want to get my choice right. I am not a race car driver, I am often steady on my commute to work. However the M does come out to play and I do 'give it the beans' as it were on some of the twisty roads near me when I get the chance. The car is garaged most of the time and it's based in the UK so not experiencing the extremes of climate really. Max range I guess would be -15C (AT A PUSH) to 30C (no laughing, I know it's the UK but this does happen every now and then).

My questions are as follows:

1 - Is Castrol EDGE 10W-60 really identical to Castrol TWS?
2 - The reason for the oil change from TWS to 5w30 is alleged to piston ring design changes, does this seem plausible to members on this board?
3 - Some allege the that S62 (E39 M5) engineering recommendation even for post March 2000 engines is still TWS and not 5w30 does anyone know of its origin or agree with this recommendation?
4 - Is the TWS and 5w30 choice a major decision bearing in mind my driving style, i.e. is there a difference for me?

I'd encourage any expert or enthusiast opinions and additional knowledge. I am here to learn not stamp my own point of view that's why I am asking

I would also like it if others with the same questions as I have would contribute too with what they have heard.

Thank you all in advance.. I hope this hasn't been covered before.. if it has please put up a link I can follow..

Regards

Craig

 

[Quattro Pete]

Welcome to BITOG.

I've seen this post from m5board.com referenced here not that long ago...
https://bobistheoilguy.com/forums/threads/discussion-about-bmw-e39-m5-s62-and-tws-10w-60.123246/

but it doesn't look like it turned into a meaningful discussion here on BITOG.

BITOG search engine sucks, especially with 3-letter words. Use google instead and search within the bobistheoilguy.com domain.

As for your main questions, well... I'll leave it up to the experts.

Nice car, by the way!

 

[d00df00d]

to BITOG!

Originally Posted By: captainanonymous
1 - Is Castrol EDGE 10W-60 really identical to Castrol TWS?

That seems to be the case. Either way, Edge 10w-60 has taken TWS's place and is touted as being designed specifically for BMW M engines, so I would use it with the same confidence.


Originally Posted By: captainanonymous
2 - The reason for the oil change from TWS to 5w30 is alleged to piston ring design changes, does this seem plausible to members on this board?

Absolutely.


Originally Posted By: captainanonymous
3 - Some allege the that S62 (E39 M5) engineering recommendation even for post March 2000 engines is still TWS and not 5w30 does anyone know of its origin or agree with this recommendation?

It depends on your oil temps. If you're running the car at high speed every day, you probably want TWS/Edge 10w-60. Otherwise, either oil should do just fine.

I have heard that BMW's M engineers like to spec oils for the highest possible oil temps, and that that is the main reason why most M engines spec TWS. If BMW engineers ever did say that all S62s should take TWS regardless of year, I'd bet that that's their reasoning.


Originally Posted By: captainanonymous
4 - Is the TWS and 5w30 choice a major decision bearing in mind my driving style, i.e. is there a difference for me?

The 5w30 is probably fine, especially given that you are not consistently aggressive and don't see really hot ambient temps. However, the 10w-60 wouldn't hurt.

One caveat: If you do want to switch oils, wait for at least a couple of oil changes before you judge oil consumption. Switching oils can cause consumption to spike.

Hope that helps, and interested to hear what others say.

 

[J_Myler]

I have no information on this topic, But I'd like to say

 

[Alex38]

I also have no M5 experience, but I would like to say NICE CAR!!! I've always liked those!

 

[MCompact]

I'm thinking about picking up either an E39 M5 or an E46 M3. In both cases I'd go with Castrol EDGE 10W-60; it certainly can't hurt.

 

[captainanonymous]

Ok.. so are we saying that there will be not detrimental effects using TWS rather than 5w30 in a post 2000 E39 M5 engine? I mean these oils must have radically different characteristics surely? If so surely one oil has an advantage over the other?

I am a bit confused here, I have also been told that the 5w30 that BMW use is actually a bit thicker than a run of the mill 5w30 and in real terms behaves more like a 5W-40.. I really don't know enough about this subject to be able to say anymore. I just want to try to get the oil choice for my engine right.

Thanks

Craig

 

[d00df00d]

Originally Posted By: captainanonymous
Ok.. so are we saying that there will be not detrimental effects using TWS rather than 5w30 in a post 2000 E39 M5 engine? I mean these oils must have radically different characteristics surely? If so surely one oil has an advantage over the other?

The main advantage of TWS over the 5w30 is protection at very high temps.

The main advantage of the 5w30 over TWS is lower viscosity, which translates to better flow on a cold start, reduced drag, and better cooling.

If you always see very high oil temps, you will want TWS. It will still flow well enough when cold to be worth having for the protection it offers.

If you drive moderately most of the time, and hard only for short bursts, you will want the 5w30. It will protect well enough under those conditions to be worth having for the cold properties, low drag, and better cooling it offers.


Originally Posted By: captainanonymous
I am a bit confused here, I have also been told that the 5w30 that BMW use is actually a bit thicker than a run of the mill 5w30 and in real terms behaves more like a 5W-40.. I really don't know enough about this subject to be able to say anymore. I just want to try to get the oil choice for my engine right.

BMW 5w30's viscosity at 100 deg. C is close to the upper boundary of the SAE 30 range. This makes it a "borderline SAE 40" at high temps. It is also highly shear-stable, which means its viscosity will remain constant with use unless it is diluted (e.g. with fuel).

By contrast, the viscosity of an xw-40 with a low winter rating (e.g. 0w or 5w) will typically be in the lower half of the SAE 40 range at 100 deg. C. It will also be less shear stable, so it might become a little bit thinner with use, and might end up in the SAE 30 range after a while.

 

[captainanonymous]

Thanks d00df00d,

I have some more questions, my driving and temperatures are like this.

Stopped in traffic for a while I might get close to 100C (just shy of) for oil temperature, my water temperature will perhaps go up to half way. When driving or cruising down a motorway my oil temperature is around 80, and the water temperature is probably one third to half way.

Mostly my oil temperature is around 80, and the water temp is lower than half. Even when pushing the car I don't see these temperatures climb much at all, the cooling seems to keep the car oil and water temperatures relatively stable.

My driving at the moment I would say is mostly commuting, the car sits around 50mph - 70mph for the majority of the 15 mile trip each way. I do bring her out to play a bit at the weekends, but even then the temperatures are fairly consistent.

It seems that TWS as a choice for me might be less appropriate? And in fact BMW's 5w30 might be a better choice?

Thanks for your time everyone. I will get some more accurate readings today for you.

Craig

 

[d00df00d]

Yeah, I'd go for the 5w30. Your usage is pretty mild, all things considered. The only time your sump temps go high is when there is very little load on the engine.

 

[d00df00d]

By the way, I just started flipping through this thread again -- I had seen it before but I wanted to take another look:

Originally Posted By: captainanonymous
For a lot of debate and information on this topic visit:

http://www.m5board.com/vbulletin/e39-m5-e52-z8-discussion/142633-what-bmw-has-say-subject-oil.html


I found two points of suspicion in the first 10 pages:

1. The OP states that the move to BMW 5w30 was so that "you could now pick up a bottle of oil at the motorway service station and feel good that you were using the "recommended oil"". I call shenanigans on that. There is a BIG difference between "recommended viscosity" and "recommended oil," and BMW has been adamant about that for years. 5w30 oils abound indeed, but I doubt all motorway service stations can be counted on to carry BMW-approved oil. I don't know how it is in the UK, but here in the US you'd be lucky to find a good synthetic.

2. The pics of the Z8 VANOS units are taken as "evidence." I'm sure I don't have to tell you that one sample from each population is meaningless as evidence. There are FAR too many variables involved, especially with an engine like that (a mighty one) in a car like that (often driven by ninnies).

The thread just seems to degenerate into just another oil discussion by passionate people in an information vacuum. Is that how the rest of the thread goes?

 

[captainanonymous]

I saw that thread too and read it.. The problem is you just don't know what do believe do you. I called 3 dealerships today, and they were consistent with their choice of TWS for a 2002 E39 M5. I did stress this and asked them to make absolutely sure that TWS was correct. I asked about 5w30 and they hadn't heard of such a thing and that it was and still is TWS in all M cars (even the new ones aparently).

So according to 3 dealerships, if I took my car in, it would get filled with TWS.

There is another guy on the forum who is quite knowledgable, Douglas I beleive his ID contains. He uses BMWs 5w30 in his car, and claims it's much better at protecting at low temperatures.

As for my temps I think it's a case of good airflow, once up to 60mph + I have found even a lot of hard wide open throttle doesn't push the oil temp up all that much. Most of the high temps are sat in traffic with no air passing through the radiator etc.. Then you hear the electric fan kick in to cool the engine down periodically till you start moving. Once moving temps return to where they usually are fairly quickly.

UGH.. Just as I think I am getting somewhere with my choice I get something that makes me change my mind.

Yes I have also found on threads on this subject degenerate into "well I use 5w30 because it's the best" or "well TWS is recommended by M sport experts" (no names, no times, no references for these 'experts') rather than providing some explaination in real terms as to the pros and cons of each. This is why I joined this forum and posed this question, to get a subjective and impartial view.

 

[robertcope]

Originally Posted By: captainanonymous
There is another guy on the forum who is quite knowledgable, Douglas I beleive his ID contains. He uses BMWs 5w30 in his car, and claims it's much better at protecting at low temperatures.


Random person jumping in to be an [censored], really, but these kinds of statements crack me up.

What scientifically valid tests has he conducted to determine that one oil is better at protecting is engine at low temperatures than another?

robert

 

[captainanonymous]

Robert,

When I wrote that I wasn't intending to provide his entire argument, I was simply saying that there is one man in particular on the M5 board who is well known as an extremely knowledgable individual when it comes to these cars. He helps a lot of members with all kinds of issues and his opinion on the oil choice for a post 2000 E39 M5 is the BMW 5w30. Since I value his opinion based on the 1000's of useful posts and detailed explainations of various issues other members have I hold this view in quite high regard, I really don't see how that's all that unusual. I suppose 'claims' is probably not the best word to use, but he has stated he believes 5w30 to be the better choice.

Some of his contributions to another thread.

"Oil consumption should not be confused with lack of engine protection. Or more appropriately, lack of oil consumption should not be confused with engine protection. Nor, for that matter, should engine operating temperature vary significantly due to different engine oils.

Oil consumption is related to oil getting by the rings - in this case, a thicker oil (TWS for instance) is "beneficial" (as measured by lack of additional oil purchases) since it flows less freely.

Engine protection is related to pumping the appropriate amount of oil to the top of the engine in the quantities necessary to form a protective film. In this case, "better" is measured by ensuring the appropriate amount of oil (volume) is delivered to the top of the engine. This is turn is determined by the oil you use and the temperature at which your engine operates.

Oil weight and operating temperature need to be matched to provide optimal protection. If you use an oil that is too thick for your temperatures then you are not delivering enough oil to the top of the engine and are thus under-protecting and causing engine damage. Likewise, too thin and oil for your temperatures will result in premature shear and your oil will breakdown very quickly. Note that of these 2 scenarios, if you use too thick an oil for your temperatures you will cause engine damage, whereas if you use too thin of an oil, you cause no engine damage, but will need to change your oil more frequently."

"If there is no difference in expected operating temperature between a pre- and post- March 2000 vehicle, then how is it physically possible that two engine oils with such widely different weights (BMW 5W30 and 10W60) can both provide adequate protection, since by definition either TWS is too thick, or 5W30 is too thin when used at the same temperature?

My hypothesis is that BMW (like Ferrari before them) recognized that the vehicles were not being used as originally expected (tracked with ~150C operating temperatures) and therefore spec'd a lower weight oil that is more in line with how they saw vehicles being used (~100C operating temps)."

He makes a consistent arguement that overall less oil will be pumped to the top of the engine with a thicker oil for a given oil pressure.

"Every pump has a capacity. This capacity is measured in terms of "head", or psi, not volume. The thicker the liquid you are trying to pump, the more pressure required to move it. When an automotive engine pump hits its maximum design pressure it "bypasses" - meaning it pumps the fluid right back into the oil sump.

This means that at any given pressure, the volume of oil moved is related to its viscosity. Since the TWS is twice as thick as the 5W30, you can only move 1/2 as much of it for any given pressure. In simple terms as it relates to an engine, pressure is directly related to rpm, and thus, for any given rpm, how much oil you move is related to its viscosity.

It depends on how much oil gets pumped to the top of the engine, and whether we like it or not, the volume of oil pumped to the top is directly related to the viscosity of that oil at the temperature at which it is pumped. If this weren't the case, we'd all be using the same gear oil we use in our differential to save money...

As I stated earlier, according to the 1 member that has installed and measured oil pressure on our cars, the maximum pressure with TWS was achieved at 5K rpm. There are only 2 explanations for this that i can imagine - pump failure, or pump bypassing due to overpressure. The latter is the assumption I made, and thus my observations from above remain true - at the point where TWS is so thick that it causes the oil to bypass, 5W30 will continue to flow in higher quantities."

I am here to learn and make an informed choice regarding my oil for the next oil change. Thanks for your contribution.