stiff lower gears selection

[Magenta Sunset]

I've read the threads ref changing linkages/bushes, but I don't think it's the answer I seek.
Engine is DW10 (90hp) with a 'right & back' reverse.
only a small niggle, but when the engine is cold, 1st & 2nd (mostly) are diff to select & release.
Seems better when engine has warmed up.
Would a 'box oil change do the trick on improving that?
thanks.

[Toms306]

Using non genuine 'box oil usually causes this. Replace it with genuine stuff and that should help!

[Magenta Sunset]

thanks Tom,
not sure what's in there. not been done since I've owned it.
(job for spring then)

[bashbarnard]

Mine does this. As tom says gearbox oil. The pug stuff has something specific in it. No idea what. Mines really bad but cba to work on it. Lol