Can I use synthetic 10-40 oil in the tranny on my K5e?

[D0N]

The owners manual says to use 10-40 oil in the tranny/clutch. It doesn't specify synthetic or regular dino oil.

Can I use synthetic mobil one or should I stick with non-synthetic oil?

I've heard that synthetic can be TOO slippery in some instances.

[1989kawasaki]

synthetic oil makes the clutch slip. or so i heard

[Motorrad]

As long as it's for 4t motorcycles with wet clutch...

[alward25]

I am using Amsoil motorcycle 10w40 with no slippage problems.  I would not run Mobile 1 if it was free.  You can use synthetic, just have to use the right one. Motorcycle formulas are made for wet clutch systems.  Look for the seal that specifies the oil certifications.  If it says "energy conserving" it has friction inhibitors that will cause your clutch to slip.  If it does not say it it is worth a try.  I also like Rotella 15w40.  Good, cheap and you can find it anywhere.  Oil usage topics are always to open to hot discussion.  Everyone has their own opinion.  Might have to try a few to get what you want.
Good luck
Alex

[D0N]

thanks

[Polar-Bus]

I am also not a fan of running a full synthetic in a wet clutch type gearbox.  If you have an older tired clutch you could have potential slipping issues. I've been using Spectro Clutch Saver SX for years with excellent results.  Many of those "bling" race full synthetics get real expensive for a qt. as well !   

[Hillclimb#42]

I have wasted a clutch with my first and last try with synthetic auto oil. Its not a myth. Teflon and other friction fighters are designed to bond to metals. Standard oil is good for me.  Clutches last a long time with basic oil. Cheaper changes too, Polar

[Motorrad]

I have wasted a clutch with my first and last try with synthetic auto oil. Its not a myth. Teflon and other friction fighters are designed to bond to metals. Standard oil is good for me.  Clutches last a long time with basic oil. Cheaper changes too, Polar

Car oils just aren't beefed up with the extra high pressure additives, intended for use in a transmission. Not sure why everybody insists on using them in their bikes???

Sure the OLD honda and KX manuals state it.. BUT thats before the advent of good motorcycle specific oils with shear strength, and good friction modifyers.. the demands of a motorcycel gearbox are a far cry from what auto oil is designed for...

If you want to argue this.. I have manuals for my old Bultacos that tell you to use DRAIN OIL out of your car for mix in the fuel.. YES USED DRAIN OIL... know why?   It was fine back then... but times change.. and oil changes.

Also stating that by using synthetic auto oil, caused your clutch to slip, so all synthetic is bad? Well auto oil is differant, not designed for clutch, Motorcycle synthetics are, and have the friction modifyers to make them work properly.. and not swell the clutch plates.

You cant blame all synthetic oils for User error...

[kaw rider]

when i used amsoil synthetic bike oil in my 450 it would drag the clutch at the starting line. when i used non synthetic it would go away.