Full is 3/4 of an inch below the inlet.

 

On your miles per tank, have you recalibrated for the different tire sizes so your speedo/odo are correct? If not, and you are just going by what the odo says, then you are off on the number of miles driven for that tank... With the taller tires, you record less miles then actual.

Mitch

 

75W90 is not the correct grade for the rear, only the front. The rear requires 75W140 full synthetic.

 

Yeah but Amsoil's severe gear 75W90 is the extended drain interval and can be used for that application...at least I hope so lol

 

why don't you just follow ford's specs. an "expensive" bottle of fluid is a lot cheaper than a new ring and pinion installed...

 

You can only use 75W90 in a Dana EX80. From the Amsoil application chart (1997 F-150 5.4):

Differential, Front .....GL-5
All Temps......80W-90
SAE 80W-90 Synthetic Gear Lube
Severe Gear 75W-90
SAE 75W-90 Synthetic Gear Lube
Standard Differential, Rear Dana Axle EX 80.....GL-5
All Temps......80W-90
SAE 80W-90 Synthetic Gear Lube
Severe Gear 75W-90
SAE 75W-90 Synthetic Gear Lube
Controlled Slip Differential, Rear Dana Axle EX 80.....GL-5*[2]
All Temps......80W-90
SAE 80W-90 Synthetic Gear Lube
Severe Gear 75W-90
Controlled Slip Differential, Rear Ford & Dana 80.....GL-5*[2][3]
All Temps......75W-140
Severe Gear 75W-140
Standard Differential, Rear Ford & Dana 80.....GL-5[3]
All Temps......75W-140
Severe Gear 75W-140
SAE 80W-140 Synthetic Gear Lube

Notes:

[2] CS IDENTIFICATION: Letter & number on plate on door lock
pillar. (Models W/ Traction-Lok Rear Axle Add 4 oz of
friction modifier part no. C8AZ-19B546A (EST-M2C118-A)

[3] Synthetic oil is required.

Don't ask me how to tell whether you have a EX80, 80, or Ford rear, sorry. I'm not that smart.

 

lol their severe gear is the "expensive" bottle...

But I can't believe I didn't even think about the difference between the size of the tires/wheels in the mileage...that must be it. What exactly is involved in recalibrating it to be accurate? Is that something I can do myself?

 

Delirium,

Most of us, myself included, re-calibrate our vehicles with hand-held programmers. After my lift, larger tires, and new gears; I simply plugged in my SCT X3 while I was still at the shop. I drove off with correct speedometer & odometer readings.

 

how does it know how much to adjust it though? Wouldn't you have to enter the new diameter of the tires or the new gear ratio or something? How much does that thing cost anyway?

 

http://www.troyerperformance.com/cgi...catalogno=3000