Diff Replacement Oil

[m80]

After finally getting the damaged plugs out I've put some more 75 / 90 into the diff.
It has been making some noise and some vibration under acceleration, I think. It now seems improved some.
So I'm looking to totally replace.

Fuchs TITAN Gear Hyp 90 Hypoid Gear Oil GL5 80W-90 GL-5 80W90 4 Litres 4L 5031131237725 | eBay
This looks like the right stuff.
But I'm considering an additive to perhaps improve it further, assuming it has some wear at 123k miles.
Muscle Car ANTI-FRICTION Engine Gearbox Diff OIL ADDITIVE Ametech METAL-TEC10 | eBay

Any thoughts?

 

[johnsco]

But I'm considering an additive to perhaps improve it further, assuming it has some wear at 123k miles
Any thoughts?

My thoughts are . .. If it has some wear, no additive is going to repair the wear.
The additive is unlikely to add much to a full diff-lube change.
I would be inclined to save my money.

 

[Bellow]

The oil I'd use/recommend has a LWI of 77 and Weld Point of 400kg. Both are higher than all the compared additives in the linked page and is oil - not just raw anti-wear additive.
Proper oil or inferior oil dosed, I know which I prefer.

 

[Teego]

^^^^ Best oil is always the best thing. A full change should also get rid of any crud in there.

 

[m80]

The oil I'd use/recommend has a LWI of 77 and Weld Point of 400kg. Both are higher than all the compared additives in the linked page and is oil - not just raw anti-wear additive.
Proper oil or inferior oil dosed, I know which I prefer.

Thanks for that, a link would be appreciated.

 

[Bellow]

Thanks for that, a link would be appreciated.

This >> https://www.lelubricants.com/lit/flyers/1601-1610_1302_1304 New Duolec.pdf is the oil but it shows different results as it is a different test (not ASTM D2783-88) and the copy I have on file showing ASTM D2783-88 results - I don't know how to post here.

The oil is available in the UK, £28.65 / litre, MOQ 17.7 litres, delivery £20.00 (all excluding VAT). If interested, I'll put you in touch with who to speak to.
(NB, I don't benefit financially).

 

[DetailerDan]

Imo I would avoid additives to be honest. I had a noisy diff on a sprinter once and I added some additive (I won't mention the manufacturer) after adding this the diff lasted no more than 40 miles and it was toast. As others have said just put in a good oil

 

[kid-jensen]

I've put additives into various diffs in the past, but sadly concluded that once you hear noise associated with wear, you can't un-hear it.

This means that even if it does quieten things down a bit (which is possible) your brain has DSP'd it such that it's clearly audible.

It's the reverse principle to getting a test-drive in a new (used) car....everything seems so quiet because it's so much better/newer than your old one.

When you come to sell it, it just sounds like a rattly old tractor, because you've tuned-into all the varous noises.
Fortunately, the next owner probably hasn't .

There was an impoverished Autocar journalist once, that was given a company car because the old heap he owned made every car he drove sound as quiet as a Rolls and faster than a McLaren... Every Road test article he wrote contained nothing but gushing praise!

 

[Bellow]

I've put additives into various diffs in the past, but sadly concluded that once you hear noise associated with wear, you can't un-hear it.

More pertinently - no oil can replace metal.
Best lubricant use is preventative not remedial.