R1150 GSA oil weight; winter to summer

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Sep 22, 2020
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My bike is a 2002 R1150GSA. Bought it August of 2020 with 5,400 miles. 25,600 currently and recently switched to “full” synthetic 5w 40 Schaefer’s OTR. This is a dry clutch bike. To date I’ve used 20/50 Casteroil summer and 15W 40 Rotella winter.

According to BMW I’m ok with a 10W or 15W 40 up to 86F. Then I’m to go to a 15W or 20W 50 weight oil. This air cooled bike runs year around at 5 bars on the temp gauge, or about 221F oil temp 98% of the time. Last summer in traffic above 100F I would run 6 bars off and on, or about 266F oil temp.

The bike makes less noise on start up and starts a little faster with the 5w 40 Schaefer’s. Nothing major, it’s just seems to like the oil. It would be nice to run the 5W 40 year around. It’s also handy because I stock it for my 7.3 Power Stroke.

I plan to keep the bike, it’s now my only bike, and I ride about 20,000 miles per year.

Here’s where I need some enlightening: What happens at, or above, 86F for me to need a heavier oil? Isn’t my engine oil temp at 5 bars 221F no matter what the air temp is?

Thanks for reading this far and thanks in advance for the help!
 
Here’s where I need some enlightening: What happens at, or above, 86F for me to need a heavier oil? Isn’t my engine oil temp at 5 bars 221F no matter what the air temp is?

Thanks for reading this far and thanks in advance for the help!
You said: " Last summer in traffic above 100F I would run 6 bars off and on, or about 266F oil temp. "

You have an air cooled engine, so what happens is the oil runs hotter, which makes the oil thinner and therfore the level of protection between moving parts less.
 
Alright, that seems reasonable, 50 weight is insurance for heat spikes above the normal operating temperature.

I understand that a xW 50 Synthetic is the typical answer year around. That is likely where I will end up. I do have a couple more related...

Is adding a “Molly” a way to increase the 40w to a 50 for summer?

I’ve read about varying thickness of oils within the same weight category. If I understand correctly, there will be “thick” 50 weight oils and thin 50’s. Could you direct me to instructions on how to read the oil manufactures data to determine this?
 
I’ve read about varying thickness of oils within the same weight category. If I understand correctly, there will be “thick” 50 weight oils and thin 50’s. Could you direct me to instructions on how to read the oil manufactures data to determine this?
Look at the KV100 spec. That's the oil viscosity (units of centistokes, cSt) at 100 deg C (212 F).
 
Be aware that the engine oil in your bike may weep onto your dry clutch via a compromised rear main engine seal. It happened to me and a new clutch is expensive.

Some oils tend to weep past seals more than others. I learned that the hard way.
 
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Alright, that seems reasonable, 50 weight is insurance for heat spikes above the normal operating temperature.

I understand that a xW 50 Synthetic is the typical answer year around. That is likely where I will end up. I do have a couple more related...

Is adding a “Molly” a way to increase the 40w to a 50 for summer?

I’ve read about varying thickness of oils within the same weight category. If I understand correctly, there will be “thick” 50 weight oils and thin 50’s. Could you direct me to instructions on how to read the oil manufactures data to determine this?
It's because they are not weights but grades. There is a range to a grade.

And no, adding "Molly" is not a way to increase the grade.
 
I wouldn't run a 5/40 oil in any air cooled bike. Maybe in the winter it will be ok, you dont state the temperatures that you ride the bike in.
Doesnt make sense to run anything less then a 20/50 in summer.

"Isn’t my engine oil temp at 5 bars 221F no matter what the air temp is?"
NO

Im trying to understand your temperature readings. You are referring to "bars" and "temperature" How do you know 5 bars is 221 degrees and 6 bars "on or about 266" degrees?
To me that means the oil runs between 221 and 266 degrees all the time. Either way, Ill go with BMW owners manual and only run 15/20w50
Unless you do cold weather riding.

... and just reading the post about the oil weeping might be another reason to listen to BMW requirements for more heavy oil.
 
I wouldn't run a 5/40 oil in any air cooled bike. Maybe in the winter it will be ok, you dont state the temperatures that you ride the bike in.
Doesnt make sense to run anything less then a 20/50 in summer.

"Isn’t my engine oil temp at 5 bars 221F no matter what the air temp is?"
NO

Im trying to understand your temperature readings. You are referring to "bars" and "temperature" How do you know 5 bars is 221 degrees and 6 bars "on or about 266" degrees?
To me that means the oil runs between 221 and 266 degrees all the time. Either way, Ill go with BMW owners manual and only run 15/20w50
Unless you do cold weather riding.

... and just reading the post about the oil weeping might be another reason to listen to BMW requirements for more heavy oil.
Oil temperature on this bike is communicated by digital display using bars. 1 bar is 104F…. 5 bars is normal operating temperature and the 5th bar is displayed when the oil temp reaches 221F.

I ride year around. Winter rides are usually within 500 miles of home and I tent to ride south then. The coldest I’ve ridden in is 18F and not on this bike.

I’m a long distance rider most summers. This year in July I rode in 20 States and covered 9,000 miles. The hottest I saw was 106F and the bike was normally showing 5 bars. When stopped it would climb to 6 bars which is 266F. It never reached 7 bars which is 302F. The highest reading is 10 bars, 347F.

I agree with the oil weeping concern.
 
Wow!!! Your living the dream, 20 states 9,000 miles.
When I get stuck in traffic, which is rare but going to the beach is a given, if prolonged traffic, hot day, It will climb to the 260s and highest I ever saw was 270ish.
80 MPH interstate on hot days which is almost all summer long here of 90+ degree days It will run as high as 255
30 to 60 MPH on those hot days will be 230 to 245.
Temperatures measured on a digital Harley Dipstick oil temperature gauge.

I ran Mobil 1 15/50 just recently and posed the UOA in here. Wear numbers were great but it was just an "experiment" and fully intended and did go back to my 15/50 Mystik Jt8 which is a "diesel" oil.
Both good oils being the Mobil 1 was a full synthetic it made a little more "noise" then I was used to *LOL* but all was good and suspect you will love it in your bike.

Here is the UOA on the Mobil 15w50 = https://bobistheoilguy.com/forums/threads/mobil1-15w50-2014-road-king-103-h-o.334195/
Viscosity was a little lighter On the Mobil 1 then the JT8 but would be expected I guess being it was a full gas synthetic. Sounds like the M1 15/50 might be a perfect fit for you in what you were looking for.

I didnt get much riding time on the oil and changed it out because I didnt get much riding time in.. *L*
 
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dont see your location-important BUT i like a real synthetic 15-50 year around in Pa in my water cooled bonnevilles + even my air cooled 106 cu in Victory hammer. real synthetics cost more but can be safely run longer + by their nature thin less in the heat compared to conventional + fake group synthetics IMO!!
 
dont see your location-important BUT i like a real synthetic 15-50 year around in Pa in my water cooled bonnevilles + even my air cooled 106 cu in Victory hammer. real synthetics cost more but can be safely run longer + by their nature thin less in the heat compared to conventional + fake group synthetics IMO!!
 
1. Start up rattle, you need a new upgraded left side cam tensioner. It is straightforward to change and reduces most of the start up rattle. It is also supposed to help for cam chain guide life. You need to do this as Cam Guide replacement is difficult, to do it right requires removing the engine and splitting the cases. There is another way, it is less work but still difficult.

2. For winter, 5W40 rotella is great. Summer only 15W50 I use M1 and have used Castrol, (did not like it) and Valvoline VR1 Syn (liked it best) I normally just dump out the old oil, leave the filter and refill.

Rod
 
I should have said when changing to winter grade, I normally dump the old oil and do not change the filter. Every spring or 6K miles gets a new filter.
 
machinery lubrication showed a graph how oils act thin-thicken outside of the spec 40C + 100C they showed how real synthetics which are few + costly thin less in extreme heat + thickening is even worse in the cold! if it fits $$$$ a motorcycle oil like Redline 15-50 is my fav + can be left in service longer defraying the xtra cost.
 
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