What is the best engine oil to use in gs500f

[Lewis1_2_3]

Halfords have an offer on at the moment,

If you buy any of their own brand 5L oils you get a screwdriver set worth £20.

I got some last week, just done the change today.
I Wouldn’t say the screwdriver set is worth £20 but as a freebee to already fairly cheap oil it’s a pretty damn good deal.

10W/40 Part Synthetic

5W/40 Synthetic

and the free set looks like this


Cheers
Lew ;)