Diff and T-case fluid brand preference

I run the Lucas conventional in my rear diff with lsd, no additional additives.

 

I don't have an opinion on it per se. But the viscosity of synthetic is the same as the viscosity of conventional if they are rated the same. The explanation they give seems to be an opinion unique to them and certain applications and not shared by a majority of the information available.

https://www.machinerylubrication.com/Read/1290/synthetic-conventional-oils

https://www.haldimandsyntheticoil.ca/amsoil-science/motor-oil-properties/conventional-vs-synthetic/

Perhaps this is where the conventional is better than synthetic gear oil arose. Specialty application, specifically for the Ford 9" rear end with high pinion off-set that requires GL-6 rated oil. Of course the underlying theme is that conventional oil manufacturers think theirs is better and synthetic manufacturers think theirs is better.

https://www.currieenterprises.com/why-run-conventional-gear-oil

 

I used (I've only done it once in my 2017 (at 55k, it has 77k now) once and did Ravenol 75W in the transfer case. Next time I'll just use the Red Line the transfer case too.

 

Been lovin the Ams Oil over here too. I only have it in my rear diff but its goin in the other holes when I'm back home for thanksgiving. And some fresh trans fluid.

 

do yall reccomend using GL-4 or GL-5 for ther transfer case. I know the diffs use GL-5 so if it doesn't matter I might as well save the money and buy a shit load of

$39 75w-90 GL-5 Limited Slip, Ultra Long Drain 500k Miles, Manual Transmission, Gear/Differential Lubricant (1 Gallon)

75w-90 GL-5

 

Lucas severe duty in the rear (only stuff that doesn’t chatter) and mobil 1 synthetic in the front and t case

 

Well like my wife, from time to time, I too like to bring up old shit….so from what I gather, synthetic 75w90 is fine in front diff and transfer case but the rear diff in an 06 with LSD needs to be non synthetic with additives? Is this the general consensus? Does it need to be the extra tube of additives or if the bottle says “with additives” it should be fine? “Are you even listening or just staring off into space thinking about doing stuff to your truck again?!”

 

I learned this the hard way. I just drained the Mobil1 from my LSD rear and replace it with Lucas. The Land Cruiser runs Mobil1 all around and doesn't complain, the 4Runner runs Mobil1 all around and doesn't complain, but the Tundra seems to be very picky...