Oil tank problems with pics

[Yamaha3535]

My oil tank is filling up really slow. I think it is clogged up by the strainer. Also when the tank finally fills after 2 hours, when i come back the next day the oil level is in between the max and min line. I think it is somehow running back down the line and back into the reserve tank. Is this possible? Is there a check valve thru the line? I'm having a hard time removing the tank too. I removed the strap that goes along the top but it seems like it still is stuck. Is there any other attachment? Thanks

[boscoe99]

No check valve and none is needed. Only if the tank is higher than the motor which is not the case here.

You say you think the strainer is clogged. By the looks of the tank, so do I.

Why not install a new strainer and see what happens? I suspect you will be pleasantly surprised.

[Bilge Rat]

Clean/replace the strainer.
How old is the oil? Oil over time will absorb water making it thicker and much harder to flow. Thick oil will be very slow to transfer.

[Yamaha3535]

Ohhh no, the oil may be old and then i mixed new oil with the old. I'm going to try n remove the tank and clean n put new oil in it.