Thicker bar oil?

[jakey jake]

(yes, I searched first...) Now that it's warm out, my PS-401 drains the bar oil well before the fuel tank is empty. There's no adjustment, so a thicker bar oil seems the answer. Is there an additive that will do this? Or, what's the thickest bar oil?

I know this is a super old thread but hyper tough makes a super thick bar oil