I did not know, that is what their owners Manuel states. I had called EGO and was waiting for them to call me back which they just did and the woman said I should use a silicone lubricant. I asked about 3in1 and she said no. I hope this help you too. God Bless
On page 41 of the manual it says to lubricate the handle adjustment lever's pivot and spring and the back flap's spring and hinge using "light oil". These are metal and plastic parts, so any oil that is safe to use on plastic should suffice.