0W-XX vs. 5W-XX and oil for my BMW

[Takechan]

Hi guys,

This is my very first post, and i'm thrilled to having been allowed to join this forum. Skip the introduction and go to "My question", if you just want to help and are short on time - thanks!

Introduction
I drive a BMW E39 520 from 1997. The car has gone roughly 300,000 km. The engine had been replaced before I purchased the car last year, with one that had gone roughly 160,000 km, now one year later it's at about 170,000 km. I don't know how the car was driven by the previous owner, but I replaced the engine oil with 5W-40 (I forgot the brand) shortly after I received it.

Specifications
Car: BMW E39 520 1997
Engine: I6 24V 1991 cc
Owner manual recommends: Everything from 5W-20 to 15W-40 depending on the environment you live in.
Environment: Summer (25+ C), Winter (-5/-10 C)
Driving pattern: Daily trips of 2 x 10-15 km (35-40) min one way). I usually don't rev over 3,000-3,500 until the engine has gotten warm, which is probably just around when I arrive at my destination.

Engine oil
I took interest in engine oil shortly after I first changed oil last year, and I read a brilliant article by Dr. Haas, which dispels all the common misconceptions people have about oil, even here in Denmark - people told me 0W-30 and 0W-40 was much too thin for my car... yes, this was the reason I ended up scouring the internet for information about engine oil and viscosity in the first place.

My question
I'll be changing engine oil soon, and i've been doing some digging. I got very confused when I found out that 5W-XX oils of the same brand in more than one case were thinner at 40 degrees Celsius than the corresponding 0W-XX oil:

Castrol Edge 0W-30 (DK)
Product data sheet: 13-06-2007 - Viscosity @ 40C / 100C: 72.0 / 12.2 (API SL, BMW LL-01)

Castrol Edge 5W-30 (DK)
Product data sheet: 20-12-2005 - Viscosity @ 40C / 100C: 70.0 / 12.0 (API SM, BMW LL-04)

Shell Helix Ultra 0W-40 (pdf) (US)
Product data sheet: Viscosity @ 40C / 100C: 75.2 / N/A

Shell Helix Ultra 5W-40 (pdf) (US)
Product data sheet: Viscosity @ 40C / 100C: 75.0 / N/A

So I read up on the SAE J300 classification system, and found out that the XW part was determined by a Cold Cranking Simulator (CCS) where oils depending on their cranking viscosity and pumping viscosity at different temperatures (as well as a minimum viscosity at 100C) determine their rating. So can I assume that even though the 0W-XX oils i've been looking at have a slightly higher viscosity at 40C they will outperform the 5W-XX oil at extremely low temperatuers?

I'm interested in an oil as thin as humanly possible (cold), because the car only drives short trips and gets turned off as soon as it's warm. So in my case which would you recommend? The Castrol Edge 0W-30 (BMW LL-01) or the 5W-30 (BMW LL-04). I personally think i'll get the latter, unless someone provides compelling evidence that it's much thicker below 40C than the 0W-30 oil. I was actually hungering for a 0W-XX all year...

Thanks a lot for reading

*Update*
The thing is that I assumed that 0W > 5W+ would always be the best if you wanted to prevent wear at startup, but if you live somewhere where it's 40C a 5W will be thinner than a 0W oil, at least when comparing Castrol Edge and Shell Ultra Helix oils.
If only they would release viscosity charts for more temperatures.

 

[crinkles]

it sounds like you answered your own question!

these people who told you that 0w-40 is too thin - did they say if a 15w-40 is any thicker

at operating temps, no... at cold temps, the thinner the better.

 

[Takechan]

Crinkles,
Haha, no, well in true Dr. Haas style I ask them why the oil is thinner when the engine is warm, and why it's recommended to get the engine warm before you drain the oil

Anyway without knowing the viscosity of the oils below 40C I can't say for sure which one will suit me better. I just don't see why an oil that is thinner than a 0W-XX oil at 40C and 100C suddenly should be thicker at temperatures below 40C - but what do I know.

*Update*
I had a look at the product sheets again, and found something on the Castrol oils:

0W-30
Viscosity CCS @ -35 = 5,800 cp

5W-40
Viscosity CCS @ -30 = 5,800 cp

So maybe one could say that the 0W in this case only is an expression of it's ability to start an engine in a colder environment? -35 vs. -30.

I can only guess that the two oils are quite alike in terms of viscosity even below 40, except for their viscosity at very VERY cold temperatures.

What do you guys think?

 

[dnewton3]

I would think the 5w-30 would be a great all around, year round fit.

How cold does it get on a routine basis in your area? That might be the only reason to move to a "0w-xx" product.

 

[Takechan]

dnewton3,

It's been sub zero the last 2-3 months. It's been a really cold winter, and i've been driving around in -10C/14F sometimes. Usually it doesn't get this cold, but i'd guess around -5C/23F is the coldest it normally gets in end Dec. to about Feb. During the summer it's probably around 20C/68F-25C/77F and slightly warmer on when it's good weather.

 

[SpitfireS]

You can get Amsoil in the UK and its shipped through Europe.
In Europe, the UK is local

So the Amsoil SSO 0W-30 might be an option for you.

 

[Touring5]

If the "sub zero" you mentioned is celsius then any of the viscosities you mentioned would be fine. Those aren't extreme temperatures and all the oils you mentioned (I saw your post on the E39 forum @ Bimmerfest) should work well for you.

In my 528iT I've run Castrol Syntec (GC) 0w30, Mobil 1 0w40, and Rotella T Syn 5w40 with good results - with winter temps that range from single-digits (farenheit) to summer temperatures in the low 90's.

I'm curious how "peppy" a heavy E39 is with that 2 litre I-6.

 

[Takechan]

SpitfireS,
Oh I'll check it out.

Touring5,
Yeah decided to try this place for all my questions regarding engine oil instead - a lot more people and different cars.

I've ordered the 5W-30 and i'm curious to see how it'll work.

Oh and regarding the 520 let me put it this way, the 2L M52 is also used in some 3-series... It's not the most exciting you can get, but hey it's a BMW and I just love the E39 I had a 525I E34 before with a M50 and that had 192 bhp, which I thought was just "ok". I tried my friends 540 and that was just amazing!

One last thing, someone on another BMW forum mentioned LE (Lubrication Engineers) and it sounds like it's even better than what i've ordered. Anyone got any experiences with that? I'm not going to buy it because it's quite expensive.

 

[AntiMatic]

Mobil 1 0W-40

 

[Takechan]

AntiMatic,

I think M1 atleast, is the easiest to get here, but i'm not sure about 0W-40, i'll check it out though.

Maybe they also sell 0W-30?

 

[priler]

fuchs titan supersyn longlife 5w-40.this is what i would use without a doubt,including the climate you mention.


your in europe,why on earth would you want to get anything less?!you happen to have access to one of the best oils around.


if you absolutely need a 0w oil,then try the titan supersyn 0w-30.

also,try taking the long way home once in a while on the highway.steady speeds letting the oil fully warm up will pay dividens for the oil and engine.

 

[Craig in Canada]

I have had an M52B28 for about 9 years now.

From that list, I'd recommend the 5W40 and the Edge 0W30 in that order. You want to stay "heavy" - I don't believe M1 0W30 is ACEA A3 so don't use it. I suspect the Edge formula is pretty similar to GC which is heavy for a 30 and does work very well in M52s.

If your -5C winter temps can handle a 5W40 (I don't see why not), that would be my personal choice especially with your fairly high mileage.

 

[Takechan]

priler,

Actually luckily enough I can take the highway home or at least some of the way.

Craig in Canada,

Ok that sounds good because I already ordered the 5W-30 the other day! The price difference between 0W-30 and 5W-30 isn't that great actually.

Are you running 5W-40 in your BMW now?

 

[Craig in Canada]

Originally Posted By: Takechan
priler,

Actually luckily enough I can take the highway home or at least some of the way.

Craig in Canada,

Ok that sounds good because I already ordered the 5W-30 the other day! The price difference between 0W-30 and 5W-30 isn't that great actually.

Are you running 5W-40 in your BMW now?


Temps (usually) get a lot colder than -5C here, so I run GC (0W30 but high HTHS - a lot like Edge). I have run 15W40 in summer months (20-35C) before either because of running something like Auto-RX, saving money, or "just because" and it works excellently.

Even with my temps I could probably run a 5W40 year round just fine, but GC is easy to get in Canada and works very well.

 

[Takechan]

Craig in Canada,

How often do you change oil? I have one green light left in the dashboard, so i'll have to change soon according to the car.
It's been 11 months or 11,951km / 7,426 miles since the last oil change...

 

[Craig in Canada]

Originally Posted By: Takechan
Craig in Canada,

How often do you change oil? I have one green light left in the dashboard, so i'll have to change soon according to the car.
It's been 11 months or 11,951km / 7,426 miles since the last oil change...


My OCI is usually around 8000km, because that's 6 months. I like to change the oil before and after the winters we have around here and I don't drive a lot of miles. My UOAs show the oil has lots of TBN etc... remaining and could go farther.

My dad runs around 10,000km with GC in his M62TU. Again, UOAs show he could go farther.

For both of us that's about half of the BMW OLM interval.

 

[Takechan]

Craig in Canada,

Ok, I was actually considering changing oil more frequently. If I use the same oil winter/summer, does it matter when I change it? Or is it only important if you use different oils summer/winter?

The M62TU is a really nice engine! I've only driven a 540 once though hehe.

 

[Craig in Canada]

Originally Posted By: Takechan
Craig in Canada,

Ok, I was actually considering changing oil more frequently. If I use the same oil winter/summer, does it matter when I change it? Or is it only important if you use different oils summer/winter?

The M62TU is a really nice engine! I've only driven a 540 once though hehe.


While it has been debated, I feel that winter is hardest on the oil. Because of the cold there is more fuel (from running rich in "warm up mode") and water (from higher levels of condensation in the block) getting into the oil. Fuel is just about the worst thing for oil. Because of this, I always like to change after winter.

Compared to winter, summer is relatively easy on the oil. Temperatures are higher, but nowhere near exceeding the design parameters of the oil. There is less time running rich, less tendency for condensation internally, and a higher frequency of longer road trips (for me anyways) which are also easy on the oil compared to short trips and city driving.

Generally I've found that for folks with BMWs that are "keepers" changing every half OLM interval works out well. There are oils which can manage to go the full interval (GC is one of them) but I don't feel inclined to do 16,000-22,000km OCIs with any oil given my lower-than-average annual mileage. If I was racking on 50,000km per year of easy highway miles I would have a different strategy.

On the M62TU, you can rejoice in the fact that you get better front end suspension than the 540 boys.

 

[Takechan]

Craig in Canada,

That makes a lot of sense. I think i'll change oil now and then again before next winter - effectively doubling the OCI.

Thanks!

 

[BobFout]

Originally Posted By: Craig in Canada
While it has been debated, I feel that winter is hardest on the oil. Because of the cold there is more fuel (from running rich in "warm up mode") and water (from higher levels of condensation in the block) getting into the oil. Fuel is just about the worst thing for oil. Because of this, I always like to change after winter.


Have you validated this through UOA?