Which Oil ?

I just bought a 98 yz400f(so far i love it)

im trying to find out

what kind of motor

oil i should use.i am a firm

beleiver in synthetics

but im scared my clutch is gonna slip

if i use it.

anyone have any suggestions?

Many here use full synthetic oil with no problems. Just do a search here on oil and you'll get enough reading on the subject.


00 YZ426F

01 TT-R125L (my son's)

91 CR125

83 YZ490

74 Hodaka Super Combat(gone but not forgotten!)

Like Dirtdad said, it's been discussed a lot around here.

Also, if the clutch plates are well worn, ie, have glazing from getting real hot, I would change these out before going to the synthetic if only petroleum based oil has been run in the bike before. This will assure that you will not have clutch problems related to oil.

You'll find that many of us here use Mobil 1 15w50 auto oil. It's a good choice.

no matter what oil you choose change it offten i use belray semi syn 20w 50 in my 99 400 and i just did my first top end and it looked like i took it apart for nothing not a scratch on anything i was very pleased with how the inside of my motor looked also a clean air filter is just as importent as changing your oil do lots of maint it pays off in the long run

Did you do a leak down test first before you tore it down? If not, Why did you rebuild then?


Mr. Wizard says: "Go BIG, or go home!"


Just like dirtdad said it has been discussed hear and many debates pro/con.

Myself .....I tried mobile1 15/50 and had "weird clutch chatter" that was never there b4. so I switched back to Yamalube synthetic. It took me almost 3 oil changes (about 10-15hrs ttl) to get the clutch back to normal!

After about 1 1/2 yrs w/o Mobil 1 I decided to experiment.

I added 1000ml Mobil 1 15/50 and 500ml Mobil 1 10/30 .........Worked Excellent!

No clutch chatter and no slipping.

The bike did not run hot etc etc.

I don't see a reason for not sticking to this MIX .

My theory is that the thinner 10w is lubing the clutch more quickly than the 15w and the heavier oil helps in the HEAT of the desert.

Works for me so I think I will keep doing it.

This is highly debate-able but I think the main thing is to not use any oil that says "energy conserving" because of the wet clutch. I think it can also be labled as "friction modifiers"...


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