Most motorcycles use the same oil for the wet clutch, transmission, and engine. Unfortunately this oil is able to flow between each section in most motorcycles. Therefore motorcycle oil must be able to perform triple duty.
When oil is put through the squeezing between gears in the transmission, if the wrong oil is use the molecules will sheer and loose viscosity. So motorcycle oil must be very shear resistant.
If the oil is too slippery the clutch will slip. Therefore the oil must be slippery enough for the moving parts and not too slippery for the clutch. If you put an oil into a bike and the clutch slips, you will have to disassemble the entire engine and wipe down every part with a solvent to get all of the too slippery oil out. A cousin of mine put STP oil treatment in a bike and the clutch would not engage enough to go up a hill. He had to disassemble and clean the entire engine, trany, and clutch.
Many motorcycle engines are air cooled and run very hot. Therefore the oil must have the proper additives to insure lubrication when hot. Oils that are used for cars have recently undergone major changes in reducing the amount of ZDDP (a lubricant containing zinc and phosphorus) because this additive can poison (ruin) a catalytic converter. Modern car engines are designed with roller rockers and wider bearing surfaces to work with this modern oil. Old solid lifter engines and air cooled engines do not get enough lubrication with this newer oil and are quickly damaged.
In-between the double circle on the back of the bottle look to see if it is SL or SM. SL is the good old oil with enough ZDDP for air cooled engines. SM is the newer oil without enough ZDDP. Shell Rotella SM may be the only exception so far. It appears that Shell has added enough of other lubricants to still provide proper lubrication in high demanding engines.
Than said, many people have used Shell Rotella products in motorcycles with great success. One harley owner put an outrageous number of miles on his bike with Shell Rotella and the engine still showed no sign of wear. It was a while sine I read about that, but if I remember correctly it was over 900,000 miles. There was one report of someone having clutch problems with it, but that bike was known for a very light spring pressure clutch.
Shell Rotella is a very good oil. Many farmers use it in the high demanding environment inside their tractors and other farm engines. Truckers also use it. One reason you will not see advertisement for Shell Rotella is because farmers and truckers are the major users of it and they demand a great oil at a great price, and that leaves no room for advertisement.
T6 is a new improved version of Shell Rotella synthetic and it has just been recently released.
Also some Shell Rotella now has the Japanese motorcycle accepted endorsement. For years many people have used it in bikes because it is good even though it did not have the motorcycle endorsement.
What ever oil you chose you should check for others having success with it in your type of bike before you use it.
It has been a very long time since I had motorcycles. It use to be that you just put Castrol HD 30 mono grade in them and they were fine. But that was over 30 years ago. By the way Castrol HD 30 mono grade is still a very good oil.
