Whats the deal with 75w140 for the 10.5" limited slip . . . Why so expensive?
Ford dealer wants $21 a quart
Found Mobil 1 at autozone for $17 a quart

I know its synthetic but so was the 75w90 @ $9 a quart

I bought 6 quarts of the Mobil 1 to do the rear diff + install new MAG HYTEC cover and I'm around $110 with tax just for the fluid. I guess I wasn't expecting the steep price for the gear lube.

 

6 quarts to do the rear???? i used about 4 quarts.

 

Welcome to guzzle's Rear Differential Maintenance Web Page, this link may help.

 

I was blind sided as well. I had a very slight leak in the differential and decided to put a new gasket on and change the fluid.

Gasket $6.00 (come to find out I didn't even need one! Your never too old to learn) and thought this'll be pretty cheap.

4 quarts of 75-140...............$68.00! WTF! so much for cheap.

 

After seeing some gear lube comparisons, I'll be getting Amsoil Severe Gear next. Not much more than all the others and blows them away in tests. I bought a case of Royal Purple before reading the study and it didn't fare that well.

 

3 reasons:
1) Economy of scale. 75W90 is produced by the millions of gallons. 75W140 is nowhere near as common and produced in small lots.

2) Supply and demand.

3) Additives. To get performance/protection over such a wide range of temperature requires more expensive additives.

 

03_PSD: I'm installing a mag hytec diff cover. This after market cover at least doubles the capacity per mag hytec. I have looked at the sticky thread for inspiration for this project . . . good instructions with pictures.

cartmanea: Where did you find the gear lube reviews?

 

$3.99 quart at Walmart.

 

No, not for synthetic 75w-140. Even the Supertech crap is over $10/qt.

 

Mobil 1 synthetic is

 

No its not, not even the non-synthetic Mobil engine oil is that cheap.

 

Last time I got Amsoil Severe gear it was $17 a quart but now it went up a little. Took a little less than 4 quarts to fill my 10.5 with the 08' alum cover. Cost well over $100 to put Amsoil Severe gear in the front and rear diffs then I put 2 quarts of Amsoil ATF in the transfer case. Should be good for at least 75k now. 75W90 wasn't that much cheaper than 75W140. Expensive but what isn't nowadays.

 

Maghytec lies on the capacity...i bought the same cover and 6 qts. I have almost 2 qts left over, 5 qts is plenty but see what you use and post up please. Remember you need 8 oz of the additive!

 

Think,, I heard the your best bet is to not add any additive at first,,,drive the truck,,,see if it chatter's,,,and if needed,,add 2 oz of additive at a time,, untill the LS clutch's stop chattering !

 

Where can I find this and what weight are you going to use?
Thanks.