Oil gurus - a question

[atomicglock]

As some of you may or may not have read in my thread on manual hubs, I found the pinion nut on my rear axle (Dana 80) was loose and had ruined the seal. After repairs were completed I put in the appropriate friction modifier and topped up the diff. with 75W-140 syn. gear lube (took over a qt.).

Those sharper eyed individuals among us may have already noticed, that's not what's called for. I didn't realize this until I went to top up the front diff. and read the specs. According to my Haynes manual, both front and rear take 75W-90 syn.

So here's my question. Will using the higher viscosity lube cause any damage to the axles?

Thanks.

 

[atk]

Ford has been using 75w140 for years in the rear diffs. front diffs call for 75w90(or 80w90)....there should have been a tag on rear diff that will say what grade of fluid(gear oil) to use....

there is a slight chance, since your truck is a dually(dana 80),it might call for something different....you will be fine with what you have in there

 

[JLDickmon]

As some of you may or may not have read in my thread on manual hubs, I found the pinion nut on my rear axle (Dana 80) was loose and had ruined the seal. After repairs were completed I put in the appropriate friction modifier and topped up the diff. with 75W-140 syn. gear lube (took over a qt.).

Those sharper eyed individuals among us may have already noticed, that's not what's called for. I didn't realize this until I went to top up the front diff. and read the specs. According to my Haynes manual, both front and rear take 75W-90 syn.

So here's my question. Will using the higher viscosity lube cause any damage to the axles?

Thanks.

I just looked the spec up
it's 75W140 GL5 synthetic
UNLESS
it's a Dana 135
in which case, it's GL5 80W90

so, you're good to go

 

[atomicglock]

Thanks guys. I was concerned that running the higher viscosity lube in the winter might have caused a problem.

 

[Frankenstien]

Been Running Valvoline 75-140 syn for almost 300,000 miles.... Washington, Idaho, Montana winters... fortunately it doesn't get cold......