Gear oil..30 to 80wt? Which is thinner and gives smoother shifts?

Chris Long · Apr 20, 2006

I've been doing allot of searching in this forum and I'm trying to determine what the oil viscosity #'s mean and what works best for a tranny thats hard to shift. I have a 2005 YZ250 with 10 rides on it (15hrs). I love the bike but the trans doesn't want to shift up from 3rd under heavy power. The tranny oil in there has 6 rides on it and is getting dirty. The concensus after a forum search is that dirty trans oil causes hard shifting and YZ's have touchy transmissions. From now on I will make sure to change it often, but doesn anyone know what the best trans oil and oil weight to run in a bike with a sensative transmission. Is 30 wt thichker than 80 or is 80 thicker than 30?

Thanks a bunch, Chris

Masterphil · Apr 20, 2006

I'm not going to answer your question, but I'll say this: Choosing a transmission fluid for a 2T bike is a personal choice that depends on how well the tranny feels like it shifts for you.
Here is a list of things that you should probably try:
Gear oil, different weights
Non-energy conserving oils (I use M1 15-50)
ATF
Synthetic ATF
There is no problem with using any of the above fluids. Just don't fall into the trap of thinking that running a more expensive oil means you can make your change intervals longer. Cheap clean oil is better than expensive dirty oil any day. I don't leave my oil in for more than a couple hours of runtime. If I go to the track, it gets fresh oil before and after, because I like to abuse my clutch and heat is the enemy of all oils.

Maybe you have a bent shift fork.

Chris Long · Apr 20, 2006

Thats what I was wondering too, but how does a shift fork bend? I have been real easy on this bike.... just recreational riding and always using the clutch. From searching the forums I am amzed at how many people from 80's to 500's have had problems up shifting the bike while its at high R's and no one ever knows what it is. I guess I'll try a few oils and then maybe tear into it.

rosscopeeko · Apr 20, 2006

I'm not too sure that ATF is safe to use. Somebody on this forum mentioned it's not a lubricant, but rather a hydrolic fluid and as such doesn't lube your gears as well as an oil. I just bought some Chevron Delo 400 15w40 for my cr's bottom end but haven't tried it yet. I like to change my bottom end oil after every couple rides because it's cheap to do. Keep searching and reading and you'll find what you're looking for.

quik720 · Apr 20, 2006

All Im going to say about the ATF-F debate is this....
GM recommends using ATF in all T-56 6-speed manual transmissions.... The cars these are used in (Camaro's, Vipers) put down 335-500 HP. Our little bikes put out 30-60? Im pretty sure that ATF is a great lubricant, or these monster motors would make these hardy trannies seize immedialty. I for one am all for ATF-F in these transmissions. I changed from Motul Semi-Syn when I acquired the bike. It would consistantly "pop" out of second gear, Changed to ATF-F never looking back....Never pops out of gear. Shifts flawlessly!
K, I lied.... 2 things.... ATF-F is 2 dollars a quart... :cool:

DLHamblin · Apr 21, 2006

Chris Long said:
Is 30 wt thichker than 80 or is 80 thicker than 30?

Thanks a bunch, Chris

80W gear oil (Bel-Ray Gear Saver for Transmissions etc) is about like 30W motor oil in viscosity. I don't know (and have not been able to figure out why) the ratings are different for the two types of oil.

Masterphil · Apr 21, 2006

The environment inside an automatic transmission is nearly identical to that found in a dirtbike engine.

robwbright · Apr 21, 2006

My father in-law has run his own auto transmission business for 20+ years and also races a CR125 kart in the WKA series.

He says ATF is just fine for MX transmissions.

That said, I haven't switched from Mobil 1 15w50 Extended Performance because it's working nicely.

RM_guy · Apr 21, 2006

If you realy want it to shift smooth you have to do some polishing on the shifter mechinisms. You can get to the shifting star by removing the left side case cover but for the forks and drum you'll need to split the cases. You'd be suprised how much better it is with just doing the star. I run The cheapest 10W-40 I can find and change it every 2-3 rides. I'm still on the original clutch on my '01 RM250

Here are a couple of links on the subject:
http://www.dirtrider.net/forums3/showthread.php?p=275684
http://www.dirtrider.net/forums3/showthread.php?t=36113

Masterphil · Apr 21, 2006

robwbright said:
That said, I haven't switched from Mobil 1 15w50 Extended Performance because it's working nicely.

Same case for me, but I may be doing some experimenting soon.

darringer · Apr 21, 2006

I agree with trying different oils and making up your own mind. In my '02 cr I use the Honda HP trans oil, and it shifts great. I have run motor oils and atf also, but ended up going back to the Honda stuff. The tranny shifted well with everything I used, but I like the clutch feel better with the HP. Regardless of which oil is used, I have always changed it every other ride. Clean oil always works the better.

NacNac250F · Apr 21, 2006

Don't use 80W if you buy it from an auto parts store because it's probably going to be gear oil which is like syrup. IF you gonna buy 80wt oil make sure it made for a dirt bike motor because then it will be the right viscosity. Like someone else said, the dirt bike 80W oil is the same as or close to lik 10w-30 but has different number and dont have a clue why.

sunnyboy · Apr 22, 2006

use the type of oil recomended by the manufacturer--you should have an owners manual and it has this info. in it.that is all i have to say about TRANS.OIL.sounds like you have a bad transmission.one of the dogs is probably bad,if you bought the bike new and only have a few rides on it your dealer should be willing to help you out to some degree and will probably be able to tell during inspection if this is a manufacturing problem or if it is due to you,with that few rides it is probably not your falult but you did surpass the recomended oil change --i change mine every time i come home. dont waist time playing with oil when that is not the problem.you have a nice bike and it needs to be fixed so fix it

Masterphil · Apr 22, 2006

sunnyboy said:
use the type of oil recomended by the manufacturer--you should have an owners manual and it has this info. in it.that is all i have to say about TRANS.OIL.sounds like you have a bad transmission.one of the dogs is probably bad,if you bought the bike new and only have a few rides on it your dealer should be willing to help you out to some degree and will probably be able to tell during inspection if this is a manufacturing problem or if it is due to you,with that few rides it is probably not your falult but you did surpass the recomended oil change --i change mine every time i come home. dont waist time playing with oil when that is not the problem.you have a nice bike and it needs to be fixed so fix it

+0

darringer · Apr 22, 2006

sunnyboy said:
dont waist time playing with oil when that is not the problem.you have a nice bike and it needs to be fixed so fix it

Not necessarily true. I have found in the numerous bikes I have had that if the tranny oil is left in there for awhile, the shifting can become very notchy feeling. This is very noticeable upshifting under load. Also, different oils can make the tranny shift either better or worse. Therefore, I don't think it's a waste of time experimenting with different oils and see what happens. I would split the cases only after trying the simple stuff first.

Jaybird · Apr 22, 2006

If you try ATF, try Type F. The coefficient of friction is different with typeF than Dexron/Mercon type fluids.
And ATF...ALL atf's are lubricants. They are oils just like motor oils are oils.

All of the HDEO's will make for a nice smooth shift. And all if them on the shelf at WalMart are full of great additive packages, and easy on the wallet.
Delo 400, RotellaT, Delvac1300 all in 15w-40 are hard to beat in either a 2T or 4T engine.
The groupIII synthetics of those offerings will be 5w-40's. They will last a bit longer, but you should be changing out the fluid before that should even be an issue.

Many will mix an HDEO (heavy duty engine oil) like RotellaT 15w-40 with Type F ATF to smooth the shift out a bit.
If racing, I would simply use straight ATF TypeF and change out after every moto or two.

gixxer_76 · Apr 22, 2006

A different bike I know but I have had road race bikes that simply would not up shift under certain conditions. If you are use to pressuring the shifter and blipping the throttle to make the shift, it may not actually unload the tranny enough to allow a shift under extreme load.

And I fully second the thought that Gear Saver, ATF or engine oil will all protect your vitals. Shift/clutch quality is a personal preference. I just filled with Gear Saver today. It looks like ATF but feels like 10w40. We'll see how it works out.

DLHamblin · Apr 23, 2006

gixxer_76 said:
A different bike I know but I have had road race bikes that simply would not up shift under certain conditions. If you are use to pressuring the shifter and blipping the throttle to make the shift, it may not actually unload the tranny enough to allow a shift under extreme load.

And I fully second the thought that Gear Saver, ATF or engine oil will all protect your vitals. Shift/clutch quality is a personal preference. I just filled with Gear Saver today. It looks like ATF but feels like 10w40. We'll see how it works out.

I have been using the Bel-Ray gear saver since the 1980's. If you buy in bulk its really not that expensive (more than ATF but thats fine with me...).

Birken Vogt · Apr 23, 2006

I always use heavy duty 15w-40 in my CR and XR because I own diesel trucks and that's the oil I have around. Plus as has been mentioned it is really a superior quality oil. One thing I have noticed though, if I have a bike with a dead, cold engine and try to move it by pulling the clutch it is a no-go. The oil sticks the clutch together and it takes a running engine or some other appreciable force to get the plates spinning against each other. Not a big deal really just an observation.

Birken

Chris Long · Apr 24, 2006

Thanks for all the replies. I appreciate the input. I went to the dealer and asked for the recommended tranny oil for a 2005 YZ250 and they said its Yamalube 30wt gear oil which they don't carry, but he said use Yamalube 4stroke 10/50wt motor oil which is actually 30wt in a transmission. He said its almost exaclty the same thing so I bought it. I then drained the oil on my bike which was pretty dirty. I put in the new stuff and took it riding. It shifted like a dream all day and never once gave me any hard shifts or problems upshifting. I honestly believe the tolerances in these new bikes especially YZ's is so tight, you gotts have run the correct clean oil to have your trans perform as it should.

DLHamblin · Apr 24, 2006

Chris Long said:
Thanks for all the replies. I appreciate the input. I went to the dealer and asked for the recommended tranny oil for a 2005 YZ250 and they said its Yamalube 30wt gear oil which they don't carry, but he said use Yamalube 4stroke 10/50wt motor oil which is actually 30wt in a transmission. He said its almost exaclty the same thing so I bought it. I then drained the oil on my bike which was pretty dirty. I put in the new stuff and took it riding. It shifted like a dream all day and never once gave me any hard shifts or problems upshifting. I honestly believe the tolerances in these new bikes especially YZ's is so tight, you gotts have run the correct clean oil to have your trans perform as it should.

Thats what Chad Reed listed on his website as the tranny oil for his '05 YZ-250 SX bike.

Birken Vogt · Apr 24, 2006

Chris Long said:
I honestly believe the tolerances in these new bikes especially YZ's is so tight, you gotts have run the correct clean oil to have your trans perform as it should.

Just FYI tolerances refer to how much off the desired size, clearance, etc a part can be and still be considered "good", clearance is the term to describe how much space is between moving parts

Birken

Gear oil..30 to 80wt? Which is thinner and gives smoother shifts?

Chris Long

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