Shell Rotella T6 15W-40 Synthetic Oil Experiment

There are reports of synthetic engine oil causing problems for wet clutch type motorcycles (e.g., Yamaha XJs). The reported issues include drive clutch slippage and starter clutch slippage.

It seems unclear as to whether clutch slippage can be attributed to the base stock (conventional or synthetic) or the additive packages (friction modifiers). I suspect that perhaps they put in a modern automotive full synthetic which includes friction modifiers, which therefore caused the slippage.

In other words, how do we know that it’s the base stock (synthetic vs conventional) causing the slippage versus the additive package? I intend to test that.

Shell Rotella T6 15W-40 is a fully synthetic JASO rated oil with plenty of zinc, phosphorus, vitamins and minerals (data sheets available online).

The test subject is a 1982 Yamaha XJ650J with slightly over 33,000 miles on it. The bike has no history of drive clutch slippage events. There have been two starter clutch slippage events in the past two years when the bike was warm. The XJ605J is currently filled with Shell Rotella T4 15W-40 (conventional oil).

The Rotella T4 will be drained, oil filter changed, and refilled with Shell Rotella T6 15W-40.

The assessment of whether the Rotella T6 causes clutch slippage will have to be somewhat subjective. If a clutch slippage event is noticed, it will be counted. If clutch slippage events start occurring regularly, testing will conclude and the Rotella T6 will be drained, reverting to Rotella T4.

 

In we go!! Current odometer reading 33040

 

Had a starter clutch incident last week.

About 120 miles into the experiment.

Same scenario as I’ve experienced in the past. Ride home from work, stop at a store for a few minutes, warm ambient temp, hot bike - come out of store and get the can of marbles. Then grabs and starts.

Will have to see if it gets more frequent or happens when bike is not hot.

 

For what it's worth, I've been running Rotella T6 in my 2012 Honda NC700X for the last 20000 miles with great results. All my other bikes are running the Rotella T4 15W-40.

 

I really like both the T4 and the T6 products for my bikes. I have no issues with them. To each their own I say, what ever oil makes you happy, go with it.

 

I've been in T5 for the last couple years. I have no idea what the difference is. No clutch or starter issues though, so I'm happy.

 

The T5 says “synthetic blend” - so presumably some mix of synthetic and conventional base oils (??)

 

Two months and a few hundred miles into the experiment, here's the current status:
1. No drive clutch issues at all.
2. I've had two starter clutch incidents (tin can full of marbles). Both on very warm ambient temperature days (85F or above) and a hot engine.

It seems that starter clutch slippage events are more correlated to ambient temperature than anything. At this point I have no reason to suspect the T6 is making anything worse than it already was.

 

I have only had starter clutch slippage (rattle of death) when bike was REALLY cold (like freezing temps) or when battery did not have full charge. In both cases, the starter I feel does not spin fast enough for the little rods to catch under centrifugal force.
Happens on my XJ650 only when cold and my XS650 more so when battery is not fully charged.

 

Guess I must be the lucky one on the starter clutch issue, the only problem I had was the engine slipping the drive clutch at full power once I passed the magic 7000 point otherwise it's been rock solid. I'm running Pennzoil 10W-40 conventional with 2/3 can of the sTp zinc oil treatment and routinely buzz the redline under full power with no slip from either clutch pulling the front off the ground thru 1st & 2nd gears.
Today's cheap-skate oils are just as good if not better than what we were dumping in when the bikes were new.

 

I use this in my Bandit 1250S and have had no issues for the past eight yrs with it. Love the T6.

 

A slipping drive clutch doesn't sound good.

The problem with modern automotive oils is that they have anti-friction additives that kind of work against things that require friction like the drive clutch and starter clutch. Those additives are great for modern cars trying to eek out every MPG, they are not great for 80's era wet clutches and sprag clutches.

A more lengthy discussion here:
https://www.xjbikes.com/forums/threads/choosing-the-correct-oil-for-a-wet-clutch-motorcycle.43702/

 

I remember reading about the problems with the modern oils after I started having slip issues with my clutch so I dumped the charge of synthetic I was running and went with the cheap stuff and some zinc. So far it's been absolutely rock solid with the only problem being the level float sometimes hangs up when I buzz the redline then breaks free after a short time, a distant future repair project for another day. So far I've rolled 5825 miles on the clock since I finished assembling the bike and got it on the road and the only thing I've done is changed the oil & filter and shimmed down the valves. Seriously I couldn't ask for more.
Some time I really need to buzz Dan Gardner's place being only 90 miles to the south of me.

 

Any oil that is JASO certified is good to use with a wet clutch. That is part of the certification standard.

Almost all motorcycle-specific synthetics that have come out in the last 7 years will play nice with wet clutches, and that will be listed on the container.