I have a P38 2.5D with a noisy diff, would it be ok to replace the oil with new and put in a tin of STP or Wynns to try and quieten it a bit?

 

A noisy diff usually means a bearing or pinion to crownwheel mesh is defective. All the additive 'snake oil' in the world won't 'cure' the problem you will be throwing good dosh away. LR RR uses EP80/90 or 75w90 What Differential Oil? but IMO changing oil won't solve a noisy diff. You can 'mask' the noise by using heavier oil (EP140) but sooner or later the diff will fail. Best to address the cause than trying to find a mickey mouse cure.

 

Thanks for that. What happened is that I run the car on a long journey and did not realise that the oil in the front diff was very low and only realised when it started to make a noise and then found the oil low and immediately filled it up. Although after filling it up the noise did reduce the damage has already been done by then so I was hoping that the STP would have helped.