Hi Ross,

For a Yamaha EF2400IS the information provided to us is that the manufacturer is requesting the use of an API SE engine oil specification in a 10W-30 to a 10W-40 viscosity grade. With this in mind, we are recommending the use of our Small Engine 4 Stroke 10W-30 https://www.penriteoil.com.au/products/small-engine-4-stroke-10w-30-semi-syn and our Semi Synthetic 10W-40 https://www.penriteoil.com.au/products/semi-synthetic-10w-40.

What oil have you been using?

What does it say in your owner’s manual, if you have one available to you?

If you have any further questions please get in contact with us.

Kind Regards,

Tate