40 Weight oil temp ratings

[TCF1]

Hi, I've been a long time reader on the site... first post. I have a 2009 BMW R1200GS (oil cooled, 42K miles) and have been running Castrol Power1 4t synthetic10w40 in it for the last 4k miles. I'm in Maine. I ran Actevo 10w40 semi synthetic in it for about 4K miles prior. My question is about the chart in the Haynes manual (i don't have the owners manual), which states that this oil weight is only good up to 86 degrees ambient. However it states that 15W40 and 20W40 are good up to 120F, which is confusing to me as they are all 40 weight oils. Are they rating them that way because the narrower spread oils tend to shear less (though I'm not sure if that's all that true with a modern high quality oil like either Castrol, but especially the 4t)? Curious if I'm harming the bike any by running the 10w40 4t, as I do have it out in the 90sF a few times a year? I haven't had any oil analysis done on this bike.

Thanks!

 

[thastinger]

The Mobil 4T is good oil for your application. If you wanted to try something thicker, you could try M1 15-50 in it.

 

[TCF1]

Thank you thastinger, I may try the M1 next oil change. Why do they rate the 15W40 & 20W40 so much higher on the temp rating when they are all 40W?

 

[donnyj08]

Thank you thastinger, I may try the M1 next oil change. Why do they rate the 15W40 & 20W40 so much higher on the temp rating when they are all 40W?

I would say it’s based on expected shearing of the oil. The 10w40 although generally fairly shear stable is by default less shear stable than 15w40 or 20w40 of equal quality.

 

[kschachn]

The actual BMW Rider's Manual is available online.

Lots of those oil recommendation charts are based on historical oil information which may or may not be applicable today. Back in the day the VM used in typical 10W-40 oils was of inferior quality.

 

[oil pan 4]

How hot does the engine get?

 

[JavierH19]

It won't but you could see degraded shift quality happen sooner so you may have to change more frequently.

 

[thastinger]

Thank you thastinger, I may try the M1 next oil change. Why do they rate the 15W40 & 20W40 so much higher on the temp rating when they are all 40W?

I think it is pretty tough to generalize all oils, they probably shoot for the middle of the road and their info may be significantly dated by now.

 

[TCF1]

How hot does the engine get?

The gauge has bars and no numerical value, usually running right in the middle (4-5 bars) and I've seen 6 bars once or twice in traffic for short times. From what I can find on line that's something around 200-250F... but again, not entirely sure.

Edit, These are the temps associated with each bar apparently, I think the temp listed is upper range within the bar so it is probably running a bit cooler mostly than I mentioned above (ie when it gets to 6 bars its at 220 degrees or higher, up to 266). Maybe I'm misinterpreting.

0 33.5° C ..... 92° F
1 40° C..... 104° F
2 65° C..... 149° F
3 80° C..... 176° F
4 90° C..... 194° F
5 105° C..... 221° F
6 130° C..... 266° F
7 150° C..... 302° F
8 160° C..... 320° F
9 170° C..... 338° F
10 175° C..... 347° F

 

[TCF1]

It won't but you could see degraded shift quality happen sooner so you may have to change more frequently.

this year BMW is a dry clutch, has separate gear oil.

 

[oil pan 4]

The gauge has bars and no numerical value, usually running right in the middle (4-5 bars) and I've seen 6 bars once or twice in traffic for short times. From what I can find on line that's something around 200-250F... but again, not entirely sure.

Edit, These are the temps associated with each bar apparently, I think the temp listed is upper range within the bar so it is probably running a bit cooler mostly than I mentioned above (ie when it gets to 6 bars its at 220 degrees or higher, up to 266). Maybe I'm misinterpreting.

0 33.5° C ..... 92° F
1 40° C..... 104° F
2 65° C..... 149° F
3 80° C..... 176° F
4 90° C..... 194° F
5 105° C..... 221° F
6 130° C..... 266° F
7 150° C..... 302° F
8 160° C..... 320° F
9 170° C..... 338° F
10 175° C..... 347° F

266f is solid 40w territory but if you're only seeing 220f most of the time then 40w is fine. If you knew it wasn't going to get much about 220f even 30w would acceptable.
It looks like you don't need a 50w oil.

 

[Jetronic]

Hi, I've been a long time reader on the site... first post. I have a 2009 BMW R1200GS (oil cooled, 42K miles) and have been running Castrol Power1 4t synthetic10w40 in it for the last 4k miles. I'm in Maine. I ran Actevo 10w40 semi synthetic in it for about 4K miles prior. My question is about the chart in the Haynes manual (i don't have the owners manual), which states that this oil weight is only good up to 86 degrees ambient. However it states that 15W40 and 20W40 are good up to 120F, which is confusing to me as they are all 40 weight oils. Are they rating them that way because the narrower spread oils tend to shear less (though I'm not sure if that's all that true with a modern high quality oil like either Castrol, but especially the 4t)? Curious if I'm harming the bike any by running the 10w40 4t, as I do have it out in the 90sF a few times a year? I haven't had any oil analysis done on this bike.

Thanks!

SAE J300 states: 0w-40, 5w-40 and 10W-40 have a minimum HTHS viscosity (the one that matters for lubrication) of 3.5cP. 15W-40 and up have a 3.7cP minimum, same as a 50 and 60.

 

[twX]

Aside from the higher HTHS requirement for a 15W-40, it will also have less permanent shear-thinning.

Temporary shear thinning will also be lower in parts of the engine where shear rates are higher than those used for the HTHS test, like at the piston rings and cams. This makes a 15W-40 effectively thicker than a 10W-40 at these components, even if the HTHS of the two oils is the same. The W rating is just as relevant as the operating temperature grade for certain engine components.

The standard oil grade for this engine is 20W-50. I would either use that, or a 15W-40 or 15W-50.

 

[BusyLittleShop]

Given the fact that roughly 60% of total engine wear occurs during
start up before warm up because of the time it takes for cold oil to
flow from the pan to the cam...

API test multi grade oils in a Cold Crank Simulator to inform the
consumer of an oils W performance... The Simulator ranks the oils from
the fastest 0W to the slowest 20W

From the list consumers can select the oil that flows from the pan to
the cam the quickest to arrest the wear during critical start up...

Fastest from the Pan to the Cam

1)0w40
2)5w40
3)10w40
4)15w40
5)20W40

Slowest from the Pan to the Cam

 

[Overfill]

It was because of how they expected the HTHS to drop once the transmission got to shearing th oil up. Yes, in the vast majority of the "off-the-shelf" oils, higher VI oils will exhibit greater permanent shear due to greater VI%.

Mobil 1 15w-50 is a good option for these bikes. Ausfart has done nearly 100k on 20w-50 in basically the same bike...

 

[TCF1]

Thanks everyone for your replies. Based on the discussion I'd say the Acteva 10w40 I've ran for the past 6k miles over two changes was totally fine, but not technically the best option if I end up out on a real hot day. I did end up switching over to M1 15W-50 and will run that from here out.
The cold start wear argument is a good counter argument to the switch. I do use Rotella T6 in my tractor, run a lot in winter, for that reason.
Cheers

 

[Cujet]

Over the years I have been totally impressed with the results I get from M1 15w-50. It is commonly available at any WalMart, has a high HTHS of 4.5, along with adequate ZDDP 1200/1300, is absolutely capable of handling extreme temperatures without coking turbocharger bearings/hot side, will not form deposits under those roasting turbo pistons and will not produce any sludge or varnish. For those reasons, it makes for a great air cooled engine, turbocharged engine and endurance race/motorcycle engine oil.

Remember, the oil change is the only way to remove certain contaminates. Even the best oil ever made needs to be changed frequently enough.

 

[Cujet]

Why do they rate the 15W40 & 20W40 so much higher on the temp rating when they are all 40W?

As a very general rule, the higher the first number the higher the HTHS (viscosity at 150ºC/302ºF)

M1 5w-50 HTHS is 4.4, 15w-50 is 4.5.

 

[alarmguy]

...However it states that 15W40 and 20W40 are good up to 120F, which is confusing to me as they are all 40 weight oils. Are they rating them that way because the narrower spread oils tend to shear less (though I'm not sure if that's all that true with a modern high quality oil like either Castrol, but especially the 4t)? Curious if I'm harming the bike any by running the 10w40 4t, as I do have it out in the 90sF a few times a year? ...

I doubt you are harming the engine a few times a year but to your question, yes a 10 will shear down more than a 15 and 20
This is true with any oil on the market. The additives that have the oil act like a 40 break down and the viscosity moves to what the oil actually is, maybe closer to the 20 to 30 range. Less to break down in a 25 or 20, less break down.