My Ranger (8.8, 4:10 gears, LS) calls for 80w-90 for both front and rear differentials. Would there be any benefit to using 75w-140 Mobil 1, or would I be better off using the 75w-90? I don't do much towing, but obviously want the very best protection.
Differential Lube Weight Question
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AMSOIL just came out with a 75W110 that sounds like a good option for you. "AMSOIL SEVERE GEAR® (75W-110) provides superior performance and replaces competitors’ 75W-110, 75W- 90 and 80W-90 gear oils. It delivers better viscosity protection than SEVERE GEAR 75W-90 and better fuel efficiency than SEVERE GEAR 75W-140."
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Some argument can be made for "thicker is better" in diff lubes, but going all the way to 75W-140 is probably a bit extreme.
The Amsoil 75W-110 is probably an excellent balance.
The Amsoil 75W-110 is probably an excellent balance.
My 04 Marauder came with the same gear oil as yours in it. The 03 model had a TSB on the rear that called for 75W-140 which FORD supplied. I switched to Lucas 75W-90 synthetic when I put in the 4:30 gears. Now 3 years later I'm rethinking my oil weight and just may go with the Ams 75W-110, I think it may offer the protection I need with a little sacrifice on the gas mileage.
There really isn't a NEED to go to a heavier gear oil in a Ranger. However, I stick with my story that when dealing with gears thicker is better
for wear. I've got RP 75-140 in my 01 Ranger and didn't see any change in MPG or power. I've also put Mobil 1 140 in a 96 Ranger with a 3.0/auto and didn't have any complaints about loss of power/MPG.
A good 90wt is better than a cheap 140. The diffs in the Ranger are plenty big for the HP they make, any good gear oil in the correct formulation will work fine.
A good 90wt is better than a cheap 140. The diffs in the Ranger are plenty big for the HP they make, any good gear oil in the correct formulation will work fine.
How much difference can a thicker gear lube make in fuel economy ? I switched out the 75w-90 that came with my 01 Ram 1500 2WD to M1 75w-140 and it had no effect on MPG. I can understand the loss if using a thicker oil in the engine, but can the parasitic drain be that much when used in a rear diff with so few moving parts? Especially went I am pushing a 4500 pound vehicle down the road. I`m sure there is some in theory, but not enough to make a difference in the real world. Or am I wrong?
MPG issue is there when considering several million vehicles whether the individual notices it at all. Its the automakers way of squeaking by CAFE. They call it 'engineering'. Too bad they can't make lighter more efficient vehicles, or sell some with diesel engines.
So, if you want more protection, definitely use that M1 75w140 gear oil. If you want, you can thin it out with the 75w90. At 25cst, M1 isn't soooo thick. Its only a point over the 110wt spec and should shear into a 110 weight soon enough.
So, if you want more protection, definitely use that M1 75w140 gear oil. If you want, you can thin it out with the 75w90. At 25cst, M1 isn't soooo thick. Its only a point over the 110wt spec and should shear into a 110 weight soon enough.
PW01, I have to agree with Da Game. When I had the axle TSB performed on my early-build '03 Marauder, the kit came with Motorcraft 75W-140 synthetic, which tells me Ford didn't think the 80W-90 the car came with was up to the job. Since you have the same axle in your Ranger, I would definitely go for the heavier synth.
My 2000 Explorer w/8.8 diff specs 75W-140 gear oil in SYNTHETIC ONLY (big block letters). Don't know the reason, but there IS a reason.....FWIW, I use the heavier weight in all my rear diffs. Those hypoid gears are tough on lubes.....
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