Oil weight question

[GS750GUY]

Dear GS family,
In preparation for the riding season I went to my service manual to confirm the weight of engine oil I needed to do an oil and filter change.
Going to the engine section of my manual I read where I need to use 20W-50W weight oil. I was surprised at what I read because my oil filler cap says to use 10W-40W on it.
Which is correct? My manual or my filler cap? I'm not the first owner of my bike and I'm wondering now if someone has replaced the oil filler cap with another one that just happened to fit the engine.
Up to now I have replaced the oil in my bike three times in the three years I have had the bike and have been using 10W-40W based on what I was reading on my oil cap.
Is it possible I have been harming the engine by using 10W-40W? Is it possible to experience some clutch slippage by using 10W-40W instead of the 20W-50W that the manual recommends?
Again, thanks for your wisdom regarding this.

GS750GUY

[Billyboy]

Search engine.

Serious, this horse has been beaten into the ground.

[BassCliff]

Hi Mr. GS750GUY,

No harm done. I use 10w40 in the "winter" and 20w50 in the summer. Just recently I've been using a 15w40 Castrol GTX diesel oil. Synthetics are OK too. Just don't use the "energy conserving" oils (look on the label), which are usually 10w30 anyway.


Thank you for your indulgence,

BassCliff

[salty_monk]

I use 15-40w Rotella Diesel heavy duty all year round. Much longer lasting (you can feel it in the gearchange when it breaks down) than the GTX 10-40w I was using before.
This test done with identical bike & similar riding conditions etc.

Just my 2p.

Dan

[GS750GUY]

Is it possible to experience clutch slippage with the lighter 10W-40W vs the manual recommended 20W-50W ?

GS750GUY.

[C.V.]

Is it possible to experience clutch slippage with the lighter 10W-40W vs the manual recommended 20W-50W ?

GS750GUY.

I doubt it, you'll probably experience the opposite. My clutch dragged with 20w 50 and problem dissapeared when i went back to 40 weight.

[salty_monk]

It would be more likely to drag with 20-50 when cold. It could be more likely to slip if you used the wrong sort of oil with friction modifiers.... How old are your clutch springs? Most need replacing after 30 years

[lurch12_2000]

Hi Mr. GS750GUY,

No harm done. I use 10w40 in the "winter" and 20w50 in the summer. Just recently I've been using a 15w40 Castrol GTX diesel oil. Synthetics are OK too. Just don't use the "energy conserving" oils (look on the label), which are usually 10w30 anyway.


Thank you for your indulgence,

BassCliff

Come on, Mr. BassCliff, it's summer all the time where you are!!!
If I used 20w50 in my bikes up here, the bike would barely turn over in the morning for 10 months out of the year.

Excuse the Yammie, but wanted you to enjoy a pic of the 7+ ft snowbanks along my driveway on my way out for a ride yesterday. It climbed from -3F in the early AM to 35F by later afternoon. So I guess that qualifies as "summer" weather. Hope my oil wasn't too thin!!!

[rustybronco]

Basscliff, now you know what snow LOOKS like. not that puney fluff you get

[Larry D]

I think he sees it on top of the mountains near his home....

[BassCliff]

Oh you guys.....

I know "intellectually" what snow is. I've seen examples of it. I know it's cold and white and made of H2O.



It doesn't stay very long where I live. Actually, it doesn't get very close to my house. I have to go visit it up in the mountains. What we call "winter" is more like our rainy season, such as it is... 12"-14" inches on a good year. I've never done it all in one day, but it is conceivable that you could make a skydive, ski a slope, and surf a wave all in one day, riding your motorcycle in between. I think I'll put that on my "bucket list".







Thank you for your indulgence,

BassCliff

[C.V.]

Snow midget

Palomar Mt. last sunday...

[GS750GUY]

It would be more likely to drag with 20-50 when cold. It could be more likely to slip if you used the wrong sort of oil with friction modifiers.... How old are your clutch springs? Most need replacing after 30 years

Actually I have not experienced any clutch slippage, but was just curious if changing oil weight could possibly cause slippage.
My springs are probably the original springs and I plan to do a plate and spring job next winter.

What do you mean when you guys refer to "clutch drag"?

GS750GUY

[rustybronco]

Actually I have not experienced any clutch slippage, but was just curious if changing oil weight could possibly cause slippage.
My springs are probably the original springs and I plan to do a plate and spring job next winter.

What do you mean when you guys refer to "clutch drag"?

GS750GUY

When you pull the clutch lever in while in gear with the bike at a stand still and it feels like it is still wanting to move forward. (with engine running, ok?)
try it in gear, then see how it feels in neutral under the same conditions and compare.
or put it neutral, pull the clutch lever in wait a few seconds tap it into gear. slips in nice and easy or THUNK?

clutch draging=clutch not completely dis-engaged

[GS750GUY]

When you pull the clutch lever in while in gear with the bike at a stand still and it feels like it is still wanting to move forward. (with engine running, ok?)
try it in gear, then see how it feels in neutral under the same conditions and compare.
or put it neutral, pull the clutch lever in wait a few seconds tap it into gear. slips in nice and easy or THUNK?

clutch draging=clutch not completely dis-engaged

No. I'm noticing none of these above symptoms of clutch drag.
One thing I did notice though. Yesterday it was a beautiful day here.....in the mid 50's.... so I went ahead and changed my oil using the manual recommended 20W-50W.
I went for a long four or five hour ride and did notice that sometimes I was having some difficulty finding neutral. Even with the benefit of my idiot light on the dash it seemed I had to play with the foot clutch lever excessively to find neutral. This did not happen all the time, and of course after fiddling with it I would always find neutral, but was a little annoying.
Anybody have any thoughts on this neutral location issue?
Thanks!
GS750GUY