Oil Change

[Sasquatch]

I think that a few people do not grasp the meaning of Dry Sump motor! A dry sump motor does not carry all its oil in a pan under the engine like your car or truck. It carry's it in a remote tank.

Unlike a car or truck there is a scavenger pump in the bottom of the motor that pumps the oil to the tank. The scavenger pump is a low pressure pump that will pump oil even foamy oil back to the tank. Oil gets a lot of air mixed with it as it is flailed around by the crankshaft upon exiting the cranks bearings.

The tank on a dry sump system works like that oil pan on your car or truck. It allowes the air and oil to seperate and sucks air bubble free oil from the bottom of each to the high pressure pump that feeds the bearings and anything else in the motor that needs a bit of oil. That is why you should not let your oil level get extreemly low because then the high pressure pump will start pumping air bubbles that have not seperated from the oil yet. Air is not a lubricant and is bad for bearings and stuff.

So to be clear you must put oil in the tank its where the high pressure pump that feeds your bearings gets its oil from. You can put a bit in the motor if you must but it is poinless as it will just be pumped back to the tank. Yamaha recomends adding oil to the motor after an engine rebuild and if you look at the volumes of oil changes with and without oil filter change then the one for after rebuild you see that there is a lot of oil still in the motor that we do not drain out.

Adding oil to the motor does nothing to feed your bearings, you are not starting the motor up dry if you add no oil to it. Adding all your oil to the motor does start your motor up dry because now the motor has to wait for the oil to be pumped from the motor to the tank so it can be pumped to the bearings that need the oil. Warm oil in warm garage won't take long but if done in a cold garage time would be much longer.

The main reason I always point out the fact that you do not need to add oil to the motor is becuase I always hear of people filling the motor and not the tank. It stops confusion and people filling the motor with oil. Now having three quarts or liters of oil dragging and then fllailing around in the motor around the crankshaft is not what the manufature had in mind for stress on both the crank shaft and engine seals never mind that the high pressure pump now has to wait for its life retaining liquid gold.

So again if it makes you feel all warm and fuzzy to add a little oil to the motor then go for it no harm done but for sake of your motor add some to the tank and never rev the motor up after an oil change. Always let it idle for a few minutes while checking for leaks and engine faults or strange noises (if any shut down immediatly). Then shut down and check the oil level in tank. If oil level is abnormaly high or low or you found a leak or heard strange noises, there is a reason that needs to be addressed before you start it again.

I usually put in about 2 and a half liters in the tank none in the motor run and then top up to about the middle of the high low range. I find that after I take it for a ride and check it when totaly warmed up it is usually right up to the full mark or real close to it. I reason that till the motor is warmed up the way only a ride can warm up a motor that there is still a few onces or mililiters of oil stuck to various components in the engine that has not made it back to the tank. This is why I always check my oil after a ride.

Just trying to help by clearing up confusion!

 

[Indy]

Good write up.

 

[stomper]

Great write up and lots of great info that is explained in a way that even I can understand . I have always added oil to the tanks but it's nice to know why and how the oiling system works.
Thanks

 

[NorthernEdge]

I totally should've ready this yesterday morning!

 

[polarisconvert]

Great info for all.