Supreme 7000 Synthetic Plus Racing Oil SAE 20W-50

Nessism wrote: Here is another analysis on 4T saying there is similar amounts of moly to that other test... www.bobistheoilguy.com/forums/ubbthreads...4T_10w-4#Post3074142

Honestly man, you are obviously free to use whatever oil you see fit, but I don't think your moly-fear is properly placed. .

I do. Bike clutches are fibrous and the moly accumulates. IMHO, it can't do anything good in a bike engine and over time probably screws it up.

I am not a big fan of moly in general because oil companies started using it to "replace" ZDDP which they have been forced to remove. But moly is allegedly a friction reducer and ZDDP is a wear inhibitor which acts in a completely different way so moly can't replace ZDDP. Moly does indeed reduce friction if and only if it can be retained on the bearing surface, but it has always been doubtful that it does when floating free in liquid oil. I have read claims that problem has been "fixed", but I am still skeptical. If there is a positive benefit, I still would keep it away from my clutch. Just my opinion.

I've been super busy lately and preoccupied with other things than motorcycles. I was buying motor oil for my car and absent-mindedly thought I would try synthetic oil in the KZ. I thought it might be more leak prone past gaskets, but never thought about the clutch. So I changed oil with Shell Rotella Synthetic T6.

Well, through a another sequence of odd events, I found myself away from home, on the freeway, with a dead battery, and nobody around. My bike has over 40,000 miles on it, and I have known for a while, that the clutch plates must be somewhat worn. When cold, if I rock the bike with it in gear, the clutch plates sort of stick together and then let go. I figure the fiber plates are probably worn smooth, instead of having a pattern as they should. The clutch is OK for normal driving.

Anyway, I turn on the ignition, pushed the bike in first gear, and pop the clutch. The motor would not turn over, and the bike comes to a halt. Ditto for second gear. And third. Finally, in fourth gear, it turned over and started. On the way home I figured I better check the clutch push-rod adjustment. And then it dawned on me about the synthetic oil. I will check the push rod this evening, but I wonder about the oil. I have used it in my other bike with no problem. Has anybody else had clutch slippage due to synthetic motor oil?

Rotella T6 should not cause any oil related clutch problems in your KZ because it is JASO-MA compliant (see image below). JASO-MA compliant oils, whether they are non-synthetic, semi-synthetic, or full synthetic, are fine for wet clutches. I've been using JASO-MA compliant, fully synthetic Mobil-1 Racing 4t in my KZ650 for the past 9 years and have experience no clutch issues. Ed

Thanks Ed. I place a high value on your judgement about this.

Some years ago, I went on a highway trip, and after about 400 miles, I realized that my clutch was slipping at times when running hard, or uphill or against a strong headwind. I did not know about the push-rod adjustment, so I limped home. Later, I realized that the push-rod WAS keeping the clutch from completely engaging, so I adjusted it and everything was fine. But thinking back on the whole thing, I must have worn the plates quite a bit. Perhaps I should think about some clutch plates.

Everything you describe seems perfectly normal to me. Clutch plates will stick together if the bike sits for even a short while. Rocking the bike back and forth a bit with the transmission in gear and the clutch lever pulled fully in should break them loose just fine. Bump starting any vehicle is going to be easier in higher gears, though second or third is usually sufficient. At 40,000 miles the clutch should still be fine unless it has been abused. Even so, regularly checking the adjustments is always a good idea.

P.S. I have used full synthetic in my bikes for years with no adverse effects at all. My Connie had well over 60,000 miles of nothing but synthetic oil. I sold it with not one single drip of an oil leak and the original clutch was working like new, despite some enthusiastic riding.

I agree with TexasKZ. Synthetic oil isn't more "slippery". It's just more resistant to shear and it holds up better at killer high temps. Otherwise it's just oil.

Most of the time clutch slipping can be traced to sacked out springs. Get yourself a new set of OEM springs and slam them in, assuming your plates measure okay. If your clutch basket is notched out that can cause some plate sticking so check that out while everything is apart too.

Thanks Jim, if that is you. I disassembled the clutch plates; inspected; measured thickness; all was good - about 15,000 miles ago. Just normal riding since then. I checked the clutch push-rod adjustment tonight. It was still OK.

My Yamaha FZ1 has such compression that it would skid the rear tire if you let the clutch out with transmission in lower gears. I was not pushing the KZ very fast when all this happened. Maybe 7 MPH. I will just keep riding the bike and stop worrying.

I run different brands of motorcycle oil in several different bikes. I don't really notice any difference from brand to brand. But what I do notice is that when I first got into Kz's almost 30 years ago, I never had any problem with the clutches. Then some time around 2000, all of my bikes started getting difficult to shift into neutral (or at all if the bike is not moving) when really hot. This is between 3 different bikes with widely varying mileage. Even after entirely replacing one of the clutches back in 2003, the problem returned within a year or so. I was probably running Castrol car oil back in the early 1990's and switched to motorcycle oil around 2000 - 2003 (after the clutch issue already appeared).

Still have the same issue today.
I use Spectro, Castrol, Valvoline, and have tried Kawasaki brand, motorcycle-specific, non-synthetic oil.

I just replaced the disks, plates, and springs on one bike, and it felt great on the couple rides I've had so far. But I don't know how long it will last, and it's been pretty cold lately, so no hot testing yet. This particular bike has only had Spectro, but it's harder to find so I switched that bike to Valvoline. Now I'm down to 2 brands of oil.

I used Castrol car oil on my '73 Z1-900 for decades until the EPA had Castrol and other oil companies reduce the additives in such oils, additives that kept MC transmissions alive. So 20 or so years ago I started using Shell Rotella 15W-40 oil. Maybe 8 years ago I switched to AMSOIL 20W-50 MC oil, but because this oil runs hotter than AMSOIL 10W-40 MC oil (I run VDO oil temp gauges on my MCs), I now only use AMSOIL 10W-40 MC oil.

I have the original OEM clutch that Kawi put in this bike in 1972 by the way. No slippage still, but I have always kept the clutch properly adjusted since I got the bike used in 12/1974.

By the way, I notice AMSOIL synthetic oil tends to stop small oil leaks on my motorcycle engines and on my cars and trucks. Had a valve cover leak on my wife's Toyota RAV4 (140,000 miles) and decided to purchase a new valve cover gasket. But in the last few weeks that oil leak has stopped. Ditto on my '73 Z1-900 where a leak started on one of the valve cover end plugs after I had checked the valves and reinstalled all of these end plugs using Permatex high-temp gasket sealer (my favorite) - that leak has stopped to my surprise.

Installed new OEM clutch and springs 5 years ago and have since put around 45,000 miles on the bike running Shell Rotella T 15W-40 exclusively.
This year I think that I can feel the clutch starting to slip a tiny bit when powering up a hill so I plan on checking the clutch plates this Winter.
The clutch has held up very well considering that back in the day we used to burn them up pretty quickly, somewhere around 10K and replace them with Barnett's and heavy duty springs.
If the clutch plates need to be replaced I will go with another set of OEM's but keep the springs, they still have plenty of life and with Carpal tunnel syndrome I don't need or want the extra pressure on my hand.
I will continue to use the Rotella T until they screw it up by changing the formula :whistle:

Not trying to turn this into a clutch topic, but I scuff the shit out of my plates. On the cement, and under my foot, and back and forth this gives a better hold when pulling the lever. When I ride, it is either clutch in, or clutch out, except for first gear, that is the only time I will slip the clutch a little. Clutch-less upshifts with a little throttle roll off is how it works for me. Depending on where, and how you ride will depend on how long the clutch will last. Check the free length of your springs, and if in doubt, replace them. Lube the clutch cable often, as it is exposed to air, and road grime, and could be getting hung up inside. If you have rerouted your cable from the stock routing, avoid any tight bends, as this will have the cable rubbing more on the inside of the cable housing. Grease the ends of the cable fittings often,

As for oil, I still use full synthetic motorcycle oil in the 20w-50 range as a preference, and change it and the filter every 5000 miles, because I commute daily 40 miles round trip. This is about every 6 months, and I can ride year round. I check the oil level in the sight glass whenever I check tire pressures, and clean the chain.

Ride on!