Consensus on front diff oil

What do you guys use? is something like AMSoil severe gear

$30 75w-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75w-90 necessary? i know its best, but not readily available. Im at 26k and looking to change it out. I can get mobile 1, RP and other non known brands..

 

Your front diff does much less work than your rear diff so I don't think anything special is necessary. I use Valvoline Synthetic 75W90 in both diffs because I can get it cheap on sale.

 

Lucas 85w-140 Dino (this is what east coast gear supply recommends)

 

Less work, yes, but due to the ADD, the spiders are always whirring around. I'd always change it when changing the rear. Using just 1.6qt, it doesn't hurt much.

There was another diff lube thread around here that had a 'study' in it sponsored by AmSoil. Reading it with a critical eye shows that just about any full-synth diff lube is plenty fine.

 

Good to know, though subjective, whats better RP or mobile 1?

 

Agreed and that's why I always change them both at the same time.

 

Just like engine oil, it's more important that you change it regularly than which brand you use.

 

The reason im not touching rear diff, is because i just had toyota completely reseal and refill it last month. It was their third attempt at stopping rear diff leak, seems ok now. So with that said rear diff fluid is brand new, along with all the hardware

 

75W90 Redline or Amsoil (only Group V) synthetics. Change every 60k miles or do whatever you want.

 

As a previous E46 M3 owner of 12 years, RedLine oils have great initial specs, but loses its properties quick, so the consensus for redline was to change it often.
And i agree, motor oil is under much more strain that a front diff that is hardly used

 

I've heard the same - I use RedLine MT90 in my manual transmission/transfer case and change it every 30k.

 

I went with M1 just because it was more available and priced well.

 

Which properties? As in TBN? Did you do an oil analysis? All oils Dino and Synthetic will shear down to lower weights especially at the 15K BMW OCI.

The good thing with Redline is their weights are higher on the visco scale, ie their 0W20 is almost a 30wt.

FWIW, Redline is one of the only Group V polyol Ester based pure synthetics on the market.

 

I've been using Amsoil oil and gear lubes in my vehicles since the late 90's. Since I don't have any experience with other synthetics, I can offer no comparisons, but have never had a single issue with any Amsoil product.

 

Yes I know most of this only because BMW’s OG 10w-60 oil for s54’s was ester based, which they later did away with causing uproar among the community. I’m not arguing that redline is bad, it’s great for high duty cycles with frequent intervals.
I digress though, my diff doesn’t see abuse, I’ll go with rp.
Thanks for your knowledgeable input

 

CAN CONFIRM

 

Right on, any gear oil will last 60k miles. Some owners never change it for 250k

 

If only it were readily available

 

I use 75w-90 I think, Royal Purple, found in most autoparts stores

https://www.autozone.com/greases-an...nthetic-max-gear-oil-sae-75w-90-1-qt/854795_0

 

Toyota specs 75w85 GL-5