Intermittent starting issue

[Blue ass fly]

My car has started to be a pain to start
Itll splutter into life , then clear and be fine with plenty of power
Next time i start it its perfect - then another it does it again
New fuel filter fitted , new plugs
Its been used lately so not due to being laid up,and it started perfectly after its hibernation
The only thing that was changed before the fault is the oil - which i used mobile 10/50
I dont know what was in it before as i only bought it just before it was sorned last year
Ime tempted to try 5/40 incase the lifters are sticking
Any ideas / comments