New diff making noises

[luminass]

Hi all I fitted a new diff in July and it's been fine until end of past week I thought I heard a groan, not used it this week untill today all ok for 10mls then it's groaning on lock at lower speeds. I'm going I look over it this weekend but it all looked ok last time driveshafts not tight or play,
It has royal purple in it from fitting, only other kids I've done in 4 yrs of owning it it vxr brakes and 18" wheels ,
I'm waiting to chat with Rodger on Tuesday , but thought I'd ask here just incase I'm missing something obvious

[luminass]

I put a fair amount in my original diff and it didn't help that one , which modified do you recomend , last time I used Lucas oils and modifier and roger said that it isn't suited to them really , only I don't want to damage this one I was looking foward to getting to mf to have speedo and gearbox re calibrated but I don't want to drive it too much as it is

[luminass]

Thanks for replies , I chatted to roger this week and have the oil for this week end , he also suggested checking suspension set up , as I've mentioned before it had rear toe arms , hsv stamped suspension, which apparently isn't standard on luminas ,
But I've been contacted from my other topic on here and he's has emailed me lots of suspension info and on vx2 seris cars they we're fitted with toe adjusters etc , so I'll be checking and setting up over the weekend and see what happens

[luminass]

No the information says
vx series II for improved handling it has

Multi link control arms added as standard equipment
New voided the inner trailing arm bushes introduced
Rear suspension trailing arms have been revised to decrease rear wheel camber