SpitfireS

I use the Amsoil SG SAE 190 in a 4.57 diff.
Richmond, the manufacturer of the gear set, recommends 75W-140 to be used with their gear sets.

75W-110 or 75W-140 in an OEM diff is IMO both ok and a "better" choice than the popular 75W-90 oils as they all are a lot thinner than single grade SAE 90 oils.

Thick(er) gear oil is not going to hurt your diff (gears or LSD) in any way.
All it might do is hurt fuel economy, albeit very little.
Just make sure it doen's get too thick in the morning, IOW pour point.
The Amsoil SG SAE 190 has a pour point of -30C and that is way below the temp my car has to start in.
The 75W-xx oils all flow pretty good at low temps.

75W-110 is cheaper too

If you can get the LE gear oils in the UK you have another choice.
LE-1605
This oil is a single grade SAE 110, with a pour point of -24C.
It being a single grade makes it a top choice too.
The relatively high pour point could be close to the lowest temp you drive your car in, living in the UK so it may not be your #1.

Note: there is not a word about cold mornings in the owners manual or service manual when it comes to gear (diff) oil.
Honda does recommend a 5W-xx engine oil for colder climates.

Drain the oil out of your diff and check it for metal parts, metallic flakes, smell and how it looks.
Check the magnetic drain plug.
"They" shoud have cleaned that during service, if it allready has a lot of flakes on it now it would not be something to be very happy about.
Metal flakes can be seen when you pour some of that oil in a glass and shake it, then look through it.
The oil should not smell burned and should not look dark.

thewiseboatmaker

thanks for your comments spit fire, very helpful indeed
will update you all as to the results/feedback from the dealership and if my problems have been resolved..

thewiseboatmaker

ok so here are the resuts:

changed diff oil to amsiol 75w110 severe gear oil:
the results are that when hot hot (1st day test drive today) the noise is totally gone, so i can only assume the stuff that was put fresh in by honda was not up to the job when it got hot

changed gear box oil to amsoil manual STF:
seems a little slicker

changed engine oil to mobil 1 (purely because i had some to use!):
engine is a lot quieter in comparison with the shell helix the dealership put in

so overall some decent fluids seemed to have helped no end, very happy...
that was until i went to examine the car and found they had put some chip marks on the edge of my door one of my pet hates, so having taken some photos before and showing someone before leaving i shall be presenting a bill to sort that out i imagine!!!

INDYMAC

Good to hear about the gear oil change helping your situation. Pass your review of the fluids to the people on your community forum. They may have similar problems/issues.

2007 Zx-10

I'm now running Amsoil Severe Gear, MTG, and ATM, the full suite. Consider me an Amsoil "convert", although I always believed in their products, but leaned toward Mobil 1 in the engine.

Oh, and their 20w-50 racing oil is amazing in my turbo rotary, it's holding oil pressure (an indirect measure of viscosity) better than any oil I've tried, most thin out significantly within 1000 miles