Yep boys.... I am going this direction, after 300 miles on the engine.

Did a valve check/adjustment at 240 miles.

[2015 Z Force 800 53/Trail EPS]

I wouldn't. The W50s have been causing the pressure relief springs to weaken sooner as they are forced open farther. Then they start having low enough oil pressure to start blinking the light at idle. Not good. Use 0,5,10 or 15W40. No 50s in these unless it calls for it.

I wouldn't. The W50s have been causing the pressure relief springs to weaken sooner as they are forced open farther. Then they start having low enough oil pressure to start blinking the light at idle. Not good. Use 0,5,10 or 15W40. No 50s in these unless it calls for it.

Good to ponder and consider, but the difference between a 40wt and a 50wt is marginal, especially with Mobil 1, which is a super light 50wt.

I am a fan of Mobil 1, 15w50 because the viscosity index is off the charts, compared to other oils and I want extreme protection when the engine is stressed and the temps start to run hot.

I use Total 10W-50.
Recommended by cfmoto.

The 50 comes into play at high ambient temps.
This month the temps were out of control, 44C/112F in shade, 60+ on the road/trails.
We were on vacation, we did 700kms, rode the machine everyday, fully loaded 2up, pretty hard on pavement and trails, the fan was at full tilt constantly, the machine never over heated, 4 bars for a few seconds then 3. On one uphill trail low gear low speed again fully loaded it could not cool down to 3 bars, it held 4 bars on the gauge and, i swear, you could cook something with the heat that the machine was giving of.

When i got back the valves sounded a bit off, they were noisy, not clicky but noisy. (never done them prior, skipped them at first service).
I did a full service and inspection (1000kms on the odo), all fluids (except coolant) and valve adjustment (front cylinder is a major PITA btw).
Oil had become a bit brown, viscosity was good.
The machine is back at perfect working order, checked all bolts nothing loose.

Oil is cheap, if you ride the machine hard, change the oil more often.

I use Total 10W-50.
Recommended by cfmoto.

The 50 comes into play at high ambient temps.
This month the temps were out of control, 44C/112F in shade, 60+ on the road/trails.
We were on vacation, we did 700kms, rode the machine everyday, fully loaded 2up, pretty hard on pavement and trails, the fan was at full tilt constantly, the machine never over heated, 4 bars for a few seconds then 3. On one uphill trail low gear low speed again fully loaded it could not cool down to 3 bars, it held 4 bars on the gauge and, i swear, you could cook something with the heat that the machine was giving of.

When i got back the valves sounded a bit off, they were noisy, not clicky but noisy. (never done them prior, skipped them at first service).
I did a full service and inspection (1000kms on the odo), all fluids (except coolant) and valve adjustment (front cylinder is a major PITA btw).
Oil had become a bit brown, viscosity was good.
The machine is back at perfect working order, checked all bolts nothing loose.

Oil is cheap, if you ride the machine hard, change the oil more often.

Yep... bingo and my exact thoughts.

But on my ride a week ago, when we were riding the steep and nasty in 4x4 Low, most of the time, I was between 5 and 6 bars on water temp.  I think 8 bars is max on the gauge.  The engine was working really hard and was hot.

This is the exact reason I am going with Mobil 1, 15w50.


........

I run nothing but AMSOIL Signature Series 0w-40 in the engine, and AMSOIL Severe Gear 80w-90 in the trans and diffs. With this combination and by AEM 21-2011DK air filter I expect the engine to reach no less than 25,000km before needing anything more than a valve adjustment.

I wouldn't. The W50s have been causing the pressure relief springs to weaken sooner as they are forced open farther. Then they start having low enough oil pressure to start blinking the light at idle. Not good. Use 0,5,10 or 15W40. No 50s in these unless it calls for it.

Been reading for weeks and ..... with all due respect... your opinion on relief springs is BS.   I'll call it.   

Both Mobil 1 15w40, or Rotella 15W40 or 5w40 are perfectly fine for our machines.

The biggest issue is.. adjust the valves and keep them in check.   All these top shelf oils are perfectly awesome.

[2015 Z Force 800 53/Trail EPS]

With the same due respect, it really isn't an opinion. The truth that heavier viscosity oils creates higher pressures is a fact and in an attempt to maintain set pressure ranges makes the reliefs open farther, compressing the springs farther. That's just fact. Kawasaki has had issues stemming from heavier oil usage in the past and it's interesting with CFM that some with low oil pressure problems at idle find the issue fixed after oil pump and relief valve replacement where nothing was visibly wrong with the pump. Also, in many CFM manuals it has this about checking the free length of the spring during servicing where other makers don't even mention it. May be because of the design though. It's known that Chinese springs tend to collapse faster then others though:

https://www.manualslib.com/manual/2357212/Cf-Moto-Cforce-1000-2018.html?page=213

Another quick article that might be of interest is this one. I'll take a look around and post other I find in my travels of interest on this subject:

https://www.highpowermedia.com/Archive/the-oil-pressure-relief-valve-or-when-to-leave-it-alone

You all do what you want...it's your machine. All I can do is offer info.. or what I would do.

With the same due respect, it really isn't an opinion. The truth that heavier viscosity oils creates higher pressures is a fact and in an attempt to maintain set pressure ranges makes the reliefs open farther, compressing the springs farther. That's just fact. Kawasaki has had issues stemming from heavier oil usage in the past and it's interesting with CFM that some with low oil pressure problems at idle find the issue fixed after oil pump and relief valve replacement where nothing was visibly wrong with the pump. Also, in many CFM manuals it has this about checking the free length of the spring during servicing where other makers don't even mention it. May be because of the design though. It's known that Chinese springs tend to collapse faster then others though:

https://www.manualslib.com/manual/2357212/Cf-Moto-Cforce-1000-2018.html?page=213

Another quick article that might be of interest is this one. I'll take a look around and post other I find in my travels of interest on this subject:

https://www.highpowermedia.com/Archive/the-oil-pressure-relief-valve-or-when-to-leave-it-alone

You all do what you want...it's your machine. All I can do is offer info.. or what I would do.

With thousands of bikes, ATV's and UTV's on Bob is the Oil Guy.... I haven't ever found a single oil failure with Rotella of any variety or Mobil 1, 15w50 on any machine.   I am hours into my usage of M1, 15w50 and the CForce seems to LOVE IT....   

[2015 Z Force 800 53/Trail EPS]

With the same due respect, it really isn't an opinion. The truth that heavier viscosity oils creates higher pressures is a fact and in an attempt to maintain set pressure ranges makes the reliefs open farther, compressing the springs farther. That's just fact. Kawasaki has had issues stemming from heavier oil usage in the past and it's interesting with CFM that some with low oil pressure problems at idle find the issue fixed after oil pump and relief valve replacement where nothing was visibly wrong with the pump. Also, in many CFM manuals it has this about checking the free length of the spring during servicing where other makers don't even mention it. May be because of the design though. It's known that Chinese springs tend to collapse faster then others though:

https://www.manualslib.com/manual/2357212/Cf-Moto-Cforce-1000-2018.html?page=213

Another quick article that might be of interest is this one. I'll take a look around and post other I find in my travels of interest on this subject:

https://www.highpowermedia.com/Archive/the-oil-pressure-relief-valve-or-when-to-leave-it-alone

You all do what you want...it's your machine. All I can do is offer info.. or what I would do.

With thousands of bikes, ATV's and UTV's on Bob is the Oil Guy.... I haven't ever found a single oil failure with Rotella of any variety or Mobil 1, 15w50 on any machine.   I am hours into my usage of M1, 15w50 and the CForce seems to LOVE IT....   

Great! Glad it's working for you.