I just went through this. I ordered 5 tubes from Amsoil directly and they sent one and told me the rest were backordered. Really nice of them since they said on their website they were in, showed they were shipped, and it wasn't until I go the box I found out otherwise.
I ended up running to 3 different stores before finding some Valvoline durablend synth at Kragen/Shuckers/Checker.
Amsoil purple Moly (GHD). They have two versions - NLGI 1 or NLGI 2 if I recall. One's easy to find the other's not. I get mine from a guy near the edge of town who stocks quite a bit in his little shop.
Just get regular Valvoline Moly imop. Most synthetic greases are thicker and don't seem to flow as easily. The important thing is to do the front end service in the first place. I highly highly doubt spending the extra money on syn will be noticeable in any way at all, except in your wallet.
None of the over the counter syn grease has a fully adaqute amount of moly for a birfield aplication. Will it work for the most part, sure but IMO not worth the trade off just for high drop points of syn. I think Amsoil is the only syn with a 3% moly.
Ditto for the NAPA stocked Valvoline Palladium (3% Moly, but not synthetic) for my birfs and driveshafts, Mobil Red synthetic for the U-joints. The Palladium apparently meets all requirements for Caterpillar, etc and is used in the trucking, mining and heavy equipment industry, but it is still a NLGI 2 Lithium based grease, so we can use it. More solid lubricant (Moly) left behind if the grease gets pressed out or washed off is the idea I think. It is for sure is a deeper shiner black color than other Moly greases.
No hijack intended;
Just realized that my U-joints had not been greased for about 1 1/2 years or 35K miles !!
Somehow they got missed, always running here or there, forgot to buy the synthetic, couldn't find the synthetic a few times, etc,etc.
Well, did it today; surprisingly, when I greased the rear shaft out came the red I put in over a year ago, a bit dry, but not totally. However, out of one cap came some ? brown grease not really rusty grease, couldn't really tell. Might have been the kid at WalMart before I told him not to use regular grease.
The front shaft U-joints however were dry , they took a lot, and about all that came out was what I had just put in. Got me worried now. Maybe that was the source of the rumble I recently started noticing first thing in the morning, ya think? We will see.
Back to the OP's thread:
How much different would Amsoil's Synthetic 3% Moly grease be from the Valvoline Palladium ie: any significant difference in protection, less rolling resistance?? I am all for synthetics when I can find them.
I second that, if you have a high mileage 80 and have worn axle shafts (where the inner seal and inner axle meet) the thicker Amsoil will work its way into the axle making a mess of you gear oil and diff.
As soon as I stopped adding Amsoil tin the fill hole of the birf and started using dino moly, my grease in the diff went away.
I could just replace the axle shafts but why, with thinner dino lube, I have no problem.