the term Hypoid refers to the type of gearing used in a gear box. the type being that two gears shaped in a cone like shape mesh together at a 90 degree angle..
you will find hypoid gearing in EVERY differential out there.... so your saying everything differential needs hypoid gear oil? I must correct you on this
I'm afraid you are mistaken.
Hypoid cut gears refer to the fact that the centerlines of the ring and pinion are not on the same plane. Or, put another way: A hypoid gear is a spiral bevel gear with an axis that does not intersect with the axis of the meshing gear, or pinion.
Refer here:
Differentials
Most differentials are simple spiral cut bevel gears. A hypoid differential is an entirely different gear tooth profile with a much different loading requirement than a regular spiral bevel cut gear.
So no, you won't find hypoid gearing
"in everything out there". Infact, it is the exception, not the norm, and since the 90's has, apparently, fallen out of favour with many manufacturers. Which is likely why few people understand what a hypoid gear assembly is...
or why very few lubricant manufacturers make mention of hypoid differentials on their labeling or make hypoid differential oils at all.
Hypoid gear oil's only difference to regular gear oil is it has additives to prevent breakdown under high heat and high torque values applied to the gearing.
I can't agree with a statement this vague. The difference between Hypoid gear oil and regular gear oil is the additives that prevent the lubricant from being squeezed out from between the gear teeth's contact surface. A low(er) pressure lubricant will simply relocate itself when the pressure between the surfaces it's trying to lubricate becomes too great. Hypoid gear cuts produce significantly higher surface pressures than a spiral bevel cut gear. If the lubricant is always getting shoved around and the gear tooth faces are actually making metal to metal contact, yeah, you're gonna get alot of heat. So your differentials will run much hotter. And they're going to wear faster.
So thus it would be more true to say:
Hypoid gear oil's only difference to regular gear oil is it has additives to prevent breakdown under extreme pressure applied to the gear teeth's interface surfaces.
don't all gear oil's have additives (specially synthetic) to prevent breakdown under high heat and high torque? yes.
Well, yes they do. But Hypoid gears are a different breed with different requirements. Why else would you read "For Hypoid differentials" on gear oil bottles? If it didn't have different requirements, the specification in the manual would request only API GL-5, NOT the "Hypoid Gear Oil API GL-5" that it does.
Manufacturers make such a wide variety of additive packages for a wide variety of applications, I would strongly suggest to take the time and expense to find a product made specifically for your application. Hence, that if the specification requires ""Hypoid Gear Oil API GL-5" at 80w90, that is precisely what should go in. Mechanical Engineers have spent alot of time deciding what that requirement is and why.
Furthermore, EP additives required for a Hypoid gear set can be corrosive to yellow metals under elevated temperatures, usually in excess of 150 degrees F. You can see this specification in ASTM D130 test in the specs that SHOULD be available from the manufacturer. I would presume that since Toyota specs Hypoid gear oil, there are no yellow metal parts in the differential case to corrode.
However, that said you can easily understand the opposite situation: why put EP additives for a hypoid differential into a spiral bevel differential and introduce the opportunity to corrode any yellow metal parts that may be present?
Thus there are API GL-5 Gear oils and API GL-5 Hypoid Gear Oils. They are
NOT the same and should not be used interchangeably. Transmissions may often call for GL-5 spec'd oils, and many transmissions have yellow metal parts, for a specific example refer to the 1st gear thrust washer in all R series transmissions... I'm sure that will last well once the transmission gets wicked hot and the oil turns to acid for that critical and vulnerable component. When the 1st gear thrust washer dies, the whole transmission goes crunch.
I personally run lucas 85w 140 non synthetic because I put my diffs through way more extreme heat and torque values than you would normally see on a daily basis.. And if you really want to believe in additives to "solve your heat and torque issues" look at the temperature brake down range of synthetic(has additives) and non synthetic you may learn something.
The Lucas oil may be fine, it may not. Lucas doesn't seem to mention anything about Hypoid in their promotional material. If I were you, I would give them a call and tell them about your application and see what they recommend. You may also do well to learn to read the spec sheets, if the manufacturer will provide them, and understand what really is synthetic and what is dino. Synthetic is a very loose term in North America and is hardly an indication of the quality of an oil.
Regardless, it seems absolutely ridiculous to go around arguing about a specification.
If it says in the manual:
TRANSFER
Oil capacity, L (qt., Imp. qt.):
1.4 (1.5, 1.2)
Oil type:
Hypoid gear oil API GL−5
Recommended oil viscosity:
SAE 75W−90
DIFFERENTIAL (2UZ−FE engine)
Oil capacity, L (qt., Imp. qt.):Two−wheel drive models
3.05 (3.2, 2.7)
Four−wheel drive models
Front 1.4 (1.5, 1.2)
Rear 3.05 (3.2, 2.7)
Oil type:
Hypoid gear oil API GL−5
Recommended oil viscosity:
Above−18C (0F)
SAE 90
Below−18C (0F)
SAE 80W or
80W−90
Which I assure you it does, as that I copied and pasted that.
What more do you want? Do you want loading tables and surface velocity tables from which to extract your own viscosity ratings? Toyota spent plenty of money on both mechanical engineering and lubrication engineering to specify those lubricant types.
Why do I take the time to type all this crap out? Because I used to not know there was a difference either... and I firmly believed that I
"can purchase any brand of 75w 90 I would like from the local parts store." and I can throw that in and everything will be fine. Then a guy who designs industrial lubricants knocked me off my high horse and told me if I do that, I'll likely need new diffs in a few years.
I went to BOSS Lubricants a long time ago to get differential fluid and I brought the owners manual and showed them the spec... I then had a long conversation with their resident "Oil Guru": mechanical engineer, lubricant expert, and he explained to me that they do not make Hypoid differential oil. I was confused, how could they possibly not make it, it's just gear oil. But no, it is not "just gear oil", it is very specific in its requirements and it is not interchanged with anything else. It is either "Hypoid API GL-5" or it is not. He specifically stated that if it doesn't say
"for Hypoid differentials"
on the bottle, do NOT use, it is not what I need.
Go down to the parts shop and start reading labels, as I did. Most gear oil bottles say nothing about Hypoid differentials. Lots talk about EP additives and such, but very very few have any Hypoid mentioned anywhere.
Then you'll find one that says in big bold letters
"NOT SUITABLE FOR HYPOID DIFFERENTIALS"
I was like "WHAO! WHAT!"
At that point, I firmly believed the lubricant engineer at BOSS, who explained to me about all this Hypoid gear oil stuff. This is a bottle that's API GL-5 spec saying not to put it in a Hypoid diff: At least they're honest about their product!
Further searching and I located a small selection of Hypoid compatible lubricants. I chose Castrol's Hypoy-C because I could buy it by the 4L jug. Stuff stinks worse than most gear oils and not only gets on everything, is virtually impossible to wipe off of anything.
please understand what your talking about before you post info to threads that someone can be miss lead from..
I said, in no uncertain words, to check the owners manual. The owners manual is very specific of its requirements. Your insinuation to others to disregard the lubrication specifications in the owners manual is something you should be more cautious about.
"Some guy on the internet said to" is not something I enjoy hearing about when people tell me something expensive blew apart on their vehicle.
As a practicing professional, it would be unwise for me to offer any advice that contradicts best practices, which in this case, should be the manual.
When a lubrication engineer comes along and says "Hey Don, check out these calculations I did, I figure with the speed and load you told me about, you need this kind of oil to maintain the film thickness required in your application, I had the calcs checked by my friend Bill, he says it's genius, and he's been doing this stuff for 10 years".
I'll be all over that oil like a fat kid on a cup cake.
Until that day, the spec is the spec.
Do what the manual says.
Otherwise, when the diff wears out or blows up, well, have fun with that.
I fail to understand why this is even a discussion? A differential is worth what... $300 or so in gears, $700 or more for someone to set up
properly? So you want me to take the advice of some guy on the internet and
"purchase any brand of 75w 90 you would like from the local parts store" with over $2000 worth of differentials and god knows how much for a transfer case rebuild, on the line, and the advice is in direct contradiction to Toyota's specifications? Note here: Notice in the manual it says
SPECIFICATIONS. Not: suggestions, recommendations, or advice.
Sorry, but just because Jim down the street does it and his truck runs fine, doesn't mean I would. And I would never advise anyone to do something I wouldn't be willing to do myself.
The specification is the specification. Any argument to the difference of the specification shall be supported with infallible scientific evidence proven under laboratory conditions. There is no leg to stand on, in this case, to argue the specification other than anecdotal evidence, opinion, hearsay, and marketing. Anyone who would choose to
"purchase any brand of 75w90 they like" with complete disregard for what the manual specifically states the application requires, is, in my opinion and for lack of better words, not too smart.
I could go on and on.
But the spec is the spec, doesn't matter how you slice it.
My intention here isn't to rip on anyone too badly :flame:, but simply to create an "AHA!" moment. And perhaps save others from my mistakes of using the wrong diff fluid and wondering why it comes out with so much metal in it.
