Stiff door lock

[newhome]

One of the locks on my French doors is becoming very stiff to unlock. Had a look online and various links say squirt with WD40, never use WD40, use 3 in 1 oil, use graphite powder, remove the barrel and clean etc. So now I’m confused about what to do. Any tips please as the lock on the back door is the same type and the one I rely on to get in the house and that’s getting a little stiff now too. 

[ProDave]

Is it stiff all the time or is it free if you lock and unlock it with the door open?

[Declan52]

Are they uPVC. Mine are dark grey so swell in the sun and get hard to lock.

As above when the door is open do all the locking bolts move freely or are they stiff.

[Square Feet]

I don't know a great deal about French door locks, but if it is the same as many front doors - a Euro lock, then they are a doddle to replace and are very cheap.  I did one recently on a front door and was stunned how easy it was (I had to break it as I had no key).

https://www.toolstation.com/shop/p80969

 

[newhome]

No it’s stiff when the door is open too. The bolts that engage when I pull the handle up don’t seem particularly stiff. Scared myself at 11pm last night when I was fiddling with it and couldn’t get it unlocked after I had locked it with the door open. Note to self, don’t mess about with stuff late at night! 

 

They are uPVC. And it’s not hot today. Back to normal Scottish summer ?

 

 

[Declan52]

Have you tried a few squirts of 3 in 1 oil along the mechanism in the bits the bolts move up and down. Don't lock the door. Just move the handle up and down to see if it frees it up. If they don't move to the top the key is hard to turn.

[newhome]

I’ve ordered some 3 in 1 oil from Amazon. I have WD40 here but don’t think I’ve got the oil. Will give that a whirl when it comes, thanks. 

[Declan52]

No wd40 is a cleaner and will remove any grease/oil that's left. A small squirt of veg oil won't do any harm. Won't last as long as the 3 in 1 but it's still act like a lubricant.

[ToughButterCup]

This is what I use... bit expensive, but works

[newhome]

3 minutes ago, recoveringacademic said:

This is what I use... bit expensive, but works

 

Thanks. I’m not too bothered about the cost but want something that will work and won’t feck it up ...