What Exactly is Hypoid Gear Oil and Do I Need to Use It in an 8.8 Diff (’92 Ranger)?

Hey, all.

I’m a little embarrassed asking this, but what exactly is hypoid gear oil? Folks at the parts store had no clue, but the Haynes manual calls for “hypoid gear lubricant” (along with 4 oz. of anti-friction additive) to be used in the ’92 Ranger I just picked up, which has an 8.8 rear differential (not sure yet if it’s the regular 8.8, or the High Torque 8.8, but I’m assuming the former). I think I’m supposed to either used 80/90 hypoid gear oil, or 75/140. Can anyone verify this and just what does “hypoid” denote? Synthetic maybe?

Thanks!

Use full synthetic 75w140 and get some friction modifier if it’s a limited slip, and 80w90 if it’s open. All ranger 8.8s are 28 spline, all Explorer 8.8s are 31 spline.

Look up axle codes if you don’t know what you have.

Also post this in the axle forum not engine.

I believe all rear axle gears are hypoid, not too sure though exactly what that means..


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It is a style of gear tooth.

Really common for rear axles, plain ol' 80-90 gear oil is what you seek if your axle is open.

https://en.wikipedia.org/wiki/Spiral_bevel_gear

I believe that yes, it is a type of tooth. More specifically, a spiral bevel gear where the pinion is offset from the ring gear. A regular spiral bevel gear will have it's pinion in the middle, or right through the center of the ring.

You get a little more strength out of it because of the shape, and I believe better NVH as well.

As for the oil, there is a bit more sliding friction with that design so the oil has to cope with that, and possibly some high temperatures. If the oil specifies it's for "differentials" you're probably good to go. For everyday stuff and you don't have a newer limited slip (older, worn out limited slips it won't matter too much), regular ol' 75w90 will work fine. If you use it hard and put it through some abuse like towing a lot, there's some other oil options that we can get into later.

Good post. I always thought hypoid was in reference to the gear lube not the type of gear. One new thing I learned today.

gw33gp said:

Good post. I always thought hypoid was in reference to the gear lube not the type of gear. One new thing I learned today.

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X2:

beer:

gw33gp said:

Good post. I always thought hypoid was in reference to the gear lube not the type of gear. One new thing I learned today.

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Thanks to everyone who replied. Like GW33, I too always assumed it had to do with the type of oil, due to the fact that all the reference materials (Haynes manual, etc) calls for Hypoid Gear Oil. I can never find any labelling on the gear oil available at parts stores that indicates they’re specifically for use in hypoid gears, so I guess that regular old 80/90 gear oil (for use in diffs) must be okay for my 8.8 non-limited slip rear, yeah?

Yes, I believe 80/90 is technically factory spec. 5 pints / 2.4 liters. If it's for differentials, you'll be fine.

http://www.therangerstation.com/manuals/

If you have a 1995+ you can look it up in the manual. Ctrl+F and then type "Capacities" and it should get you there fairly quickly. Though really, virtually nothing has changed over the years, particularly in the axle department.

I still have to look up which 8.8 rear diff I have (I do know that it’s not limited slip), if I can find the thread here. If it turns out that mine calls for 80/90 gear oil, would this one be okay to put in it? https://shop.advanceautoparts.com/p/carquest-grease-and-lube-80w-90-premium-gl-5-gear-oil-1-gal-780-01/7070322-P?searchTerm=gear+oil

It’s a nice price (especially since I plan to change the front diff fluid as well) and specifies that it’s for diffs. I’m just a little concerned about the mention that it "contains sulfur and phosphorous additive metals.” Thanks.

rangerenthiusiast said:

I still have to look up which 8.8 rear diff I have (I do know that it’s not limited slip), if I can find the thread here. If it turns out that mine calls for 80/90 gear oil, would this one be okay to put in it? https://shop.advanceautoparts.com/p/carquest-grease-and-lube-80w-90-premium-gl-5-gear-oil-1-gal-780-01/7070322-P?searchTerm=gear+oil

It’s a nice price (especially since I plan to change the front diff fluid as well) and specifies that it’s for diffs. I’m just a little concerned about the mention that it "contains sulfur and phosphorous additive metals.” Thanks.

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that warning is for the people in California that eat, drink, or otherwise use weird stuff.
the rest of us know there are better lubricants that don't have a cancer risk while performing reproductive activities.


anything that has "GL-#" is a Gear Lube

pjtoledo said:

that warning is for the people in California that eat, drink, or otherwise use weird stuff.
the rest of us know there are better lubricants that don't have a cancer risk while performing reproductive activities.


anything that has "GL-#" is a Gear Lube

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Actually, the listing reads, "Contain sulfur and phosphorous additive metals, but no zinc, in compliance with Eaton, General Motors, Ford M2C108-C, Mack GO-H, Mack GO-G, and International Harvester 2105D and are recommended for use where an API GL-3, GL-4 or GL-5 oil is required.”

I take this to mean that sulfur and phosphorous additive metals (along with zinc) can be damaging to parts used in certain vehicles. Just need to know if it’s compatible with my truck, or if there are safer choices. Not a lecture. I used to live in CA and it’s a sh@t ton better than the Northeast or Midwest will ever be, IMO.

Thanks for the info on the “GL-#"

zink is something that flat tappet camshafts need. it used to be in motor oil until the EPA severly limited/banned it. That's why the manufacturers developed standards without it. zink additives can still be purchased for breaking in a new flat tappet cam/lifters.
I just looked at my bottle of vitamins, there is 15 mg of zink in each tablet, so I'm not sure why the EPA dislikes it.

sulfur is on the bad list in motor fuels, per the EPA all newer diesels can only use low-sulfur/ultra low/none fuel. had something to do with acid rain or whatever. gear oil isn't supposed to get out into the atmosphere so I guess its ok to contain sulfur.

not a clue on the phosphorous, Google time.

I suspect that sulfur and phosphorous are actually beneficial to lubricants, but not for so much for pollution or your health. Google time again.

pjtoledo said:

zink is something that flat tappet camshafts need. it used to be in motor oil until the EPA severly limited/banned it. That's why the manufacturers developed standards without it. zink additives can still be purchased for breaking in a new flat tappet cam/lifters.
I just looked at my bottle of vitamins, there is 15 mg of zink in each tablet, so I'm not sure why the EPA dislikes it.

sulfur is on the bad list in motor fuels, per the EPA all newer diesels can only use low-sulfur/ultra low/none fuel. had something to do with acid rain or whatever. gear oil isn't supposed to get out into the atmosphere so I guess its ok to contain sulfur.

not a clue on the phosphorous, Google time.

I suspect that sulfur and phosphorous are actually beneficial to lubricants, but not for so much for pollution or your health. Google time again.

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Thanks for your input. That’s interesting about some cams needing zinc, along with most engines/diffs needing sulfur and phosphorous. I had originally read it a different way.

Minute amounts get into the combustion chamber and create nasty emissions was my understanding. Well, NORMALLY minute amounts, some of us have engines that don't play by the rules. If it has zinc in it, it won't hurt anything.

Captain Ledd said:

Minute amounts get into the combustion chamber and create nasty emissions was my understanding. Well, NORMALLY minute amounts, some of us have engines that don't play by the rules. If it has zinc in it, it won't hurt anything.

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That’s how I’d originally read things. So, does anyone know what the implications are (if any) when using this oil in the rear diff? I’m assuming that it’s just fine.