Synthetic oil causes clutch slipping?

[Ryder988]

So I was searching through oil threads and have seen a few people saying that synthetic oil is bad and causes clutch slipping is this true or is this misleading info.

[poliisi2]

I got seriosly gearbox problem because synthetic oil or maybe it was clutch what makes problems "miss shifts and 4th gear pops out" Anyway change oil back normal 10/40 mineral oil didnt have problems so far.

[Falcon991]

Half true.

Synthetic oils have more lubricity. In other words, they are more "slippery" than mineral oils on a per-centistoke basis (a 40-weight synthetic oil lubricates better than a 40-weight conventional oil.)

The slipping clutch scenario comes more from the additives in automotive synthetics than from anything you would put in a motocross bike.

The takeaway is this = synthetics are good. Fine for your clutch. Just make sure you are using a MOTORCYCLE synthetic, not one for passenger cars.

[spdnjoe]

I've been running Rotella T full synthetic for 2 yrs now in my 426 with no problems. Also in my street bikes.

My brother runs it in both sides of his CRF450R with no problems either.

[grayracer513]

It isn't even half true. Synthetic oil is no slipperier than petroleum unless the base has been modified to be that way. Oils labeled API Energy Conserving II (ECII) MIGHT cause a clutch to slip because of the frictiom modifiers they contain, but they won't necessarily do that. Since virtually all ECII oils are synthetic, people with a poor grasp of logic equate synthetics with clutch trouble.

Any oil of any kind that carries labeling stating that it conforms to JASO MA or MA1/MA2 will absolutely not cause clutch slippage; that's what MA means. Any number of good synthetic motorcycle oils carry this certification. I have used nothing but Amsoil Synthetic Motorcycle oil or Mobil 1 Racing 4T for so long I forget when I even started, never any clutch or trans trouble.

Occasionally, you will run across a clutch that "doesn't like" a particular oil to the extent that it makes it drag or grab or some such, but in theses cases, the clutch usually has a problem, not the oil.

[cherrypicker7]

I've run Amsoil 15W40 in both my 07 WR250 and the 05 WR450, without any problems and have experienced better shifting, the 05 has a Dynaring autoclutch in it, and although there is some slippage there, I attribute it to the autoclutch and that is what it is supposed to do.

[jratcliffe3]

Occasionally, you will run across a clutch that "doesn't like" a particular oil to the extent that it makes it drag or grab or some such, but in theses cases, the clutch usually has a problem, not the oil.

If changing the oil works, its just buying time, not fixing the issue.

I've used Castrol Power 1, which is fully synthetic for the past 7 years or so, and have never had any issues in either my honda's or my yam.

I'd never go near a full mineral oil, they arent nearly as good.

[Gunner354]

I ran Mobil 1 15-50 back in 04 for a couple of years in my wr250 with zero problems. I then switched to Redline and have never had an issue.

[sconeracing]

I have ran castrol GTX oil for years with no problems what so ever

[Boostpig]

I know it definatley makes my gearbox feel notchy after the first couple of rides!

[grayracer513]

I know it definatley makes my gearbox feel notchy after the first couple of rides!

Every synthetic oil made does this to your gearbox?

[JamesYZF]

Only oil I use in my YZ250F and my YZ450F is Yamalube 10w40, and I have never had any problems running it, and its a helluva lot cheaper than synthetic. I was going to switch to synthetic, but the mechanics said to never use it. That was enough for me and won't be using synthetic ever in my machines.

[Gunner354]

Every synthetic oil made does this to your gearbox?

Really? Tried every synthetic ever made? Redline oil does not!

[QuietFlight]

Every synthetic oil made does this to your gearbox?

Really? Tried every synthetic ever made? Redline oil does not!

I believe you are making the same point.

My Amsoil synthetic has OUTSTANDING wet clutch performance, as do all of the other reputable Moto blend synthetics on the market.

[Gunner354]

I believe you are making the same point.

My Amsoil synthetic has OUTSTANDING wet clutch performance, as do all of the other reputable Moto blend synthetics on the market.

Yes, trying to emphasize a point.

[QuietFlight]

i wouldn't put it past gray to have tried just about every synthetic over the years...

[grayracer513]

No I haven't, and neither has the poster claiming that "synthetic oil" makes his gearbox notchy. Maybe the one he tried did, but not because it was synthetic.

[YZ426_F]

I come across customers all the time asking the same questions about oil. They all wonder whats the difference between car oil and motorcycle oils, full syn vs mineral.

I just shake my head when I hear someone admit they run the cheapest oil they could find at autozone in there R1, Yz, ect.. just becuase they think Motul 300v, or even factory synthic motorcycle oils are to expensive and a waste of money.

I've been running Motul 300v (10w40 full syn double ester) for awhile now and have had zero problems with it.

[gscx]

My head hurts after reading this thread....

[YZ426_F]

My head hurts after reading this thread....

Sorry, it was my first post. I figured I'd pop my cherry with something I deal with everyday at work.