I have been trying an experiment over the last 18 months which seems to work really well.
I power wash the chain after every ride, dry it with an air hose & then put on chainsaw oil with a toothbrush.
Sounds fiddley but if the engine is running & you put the bike in 1st gear its does not take long.
The toothbrush cleans off the remaining c**p & helps makes sure the chain saw oil goes right into the links.
No stretching, chains still only lift 2mm off rear chainwheel & the two bikes are used almost every week in all weathers.
Mud never seems to be an issue.
B&Q cheepo oil is all Ive ever used!
LOONAL