Front axle oil change with Amsoil Severe Gear 75W-90

[IH3444]

If Amsoil fully synthetic Severe Gear 75W-90 oil is used in the refilling of a 4WD front axle, how many hours before the next oil change under regular use?

 

[YanmarFever]

I had an engineer tell me that synthetic oil is best for gear boxes that do not get very hot or have a fast output.
He said that regular gear oil would be just as good.
He mentioned that for a mower gear head it would be fine, but for a front axle I would be wasting my money using synthetic.

 

[LouNY]

Well I guess I'm wasting money, 3 of my tractors have Amsoil Severe Gear in the front axle, and my mower has it in the rear axle. My flail mower, bush hog and snow blower all have it in their gear boxs. The most frequent change interval I've every noticed was at 100 hours from new and others were 400 hours, many have an initial change and no required interval after that.

 

[RjCorazza]

I put Amsoil 75w110 in my past two front axles, and use 75w140 in all of my gear boxes.
Most of the gear boxes get changed on a very loose schedule of every few years. The gear boxes on my diesel zero turns get changed by the book every 150 hours due to the severe service 6-8 hours per day.

 

[Ddh1961]

My LS manual says every 500 hrs using API GL4 80W, so that’s what I do. I use Valvoline conventional 80W-90 gear oil; if using full syn like Amsoil I’d have no problem extending that to 750-1000 hrs., unless the tractor manufacturer or Amsoil recommended changing it sooner.

 

[IH3444]

Thanks, Ddh1961.

 

[Mike1955]

Thanks, Ddh1961.

Oh I may be learning something here. I did not know gear oil had extended drains. I thought they were only for internal combustion engines. And when comparing Amsoil gear oil to some others Amsoil seems slicker to me. But I could save a little as yanmar fever suggests. I do know them little front ends cost to work on

 

[90cummins]

Front axles do not operate at high speed nor do they generate any significant amount of heat.
Gears do see high loads and are sized to handle it.
I personally would not waste the money on synthetics unless it was use in arctic temperatures.
I’ve operated a 4x4 pickup truck in Alaska & the differential grease literally solidifies making it difficult to get it moving after sitting overnight.
I’d use synthetics up there.
90cummins

 

[Texasmark]

Well my owner's manual for my 2011 Silverado doesn't mention fluid changes in anything but the engine for 100,000 miles.

Question is, you have a sealed system that may acquire some steel shavings from gear engagement. Since steel is heavier than oil they sink to the bottom. No composition or any outside influence to degrade oil like in an internal combustion engine other than heat. Well somewhere around 250F Dino oil starts breaking down. Syn is higher than that.....400F I think is the number. I have used a non-contact infrared meter on my gear housings and never saw one over 150F and don't remember that occurrence.

I will say this: I bought a 65 HP tractor in 2007 and the manual said use THD in the front axle and that is what it came with. In 2016 I bought a small tractor of the same mfgr. On the fill port of the front axle, the one with the dipstick, molded in the orange plug was molded 85w-90 only. That was really interesting because with the 65 HP tractor I was smoothing out a field of hard clay after plowing (breaking a field) with the large, hard clumps of sod with some (about half full) weight in the bucket on the front end in an attempt to smooth out the ride and tore up both front wheel bearings...the big ones where the gears connect.

Now what does that tell you about THD in the front axle......by then it was something I already knew. When I reassembled that front end I put 140 wt gear oil in it and that has been a decade ago and no more problems......