I think the 8000 k round trip will be alright.But if you are questionning it,you might aswell change it before you head back home.

 

If you're running synth I'd change before I left and when I get back.
Synth is easily going to last 8000 kms, especially with only highway driving.

Are you not going through the States? It's about 1000 kms shorter if you do.

 

^^^I have done the Yankee trip 12X in the last 25 years and have not been through Canada since 1987 so it's time. Also bringing back my deceased fathers arsenal so better and easier going through Canuckland