Front and Rear Diff fluid change

[DougR]

I would ask them if quality conventional or synthetic gear oil would provide equivalent or better protection against wear and damage than their specified oils.

Toyota Corporation would have to perform a lot of time consuming expensive testing to answer your question. This would delay new product releases. Legal issues aside, there is no incentive for Toyota Corp to look at all the various oil formulations and grade them.

I think the overall R&D process goes something like this … (1) engineering proposes a new design or design improvements, (2) a lubrication specification is written and oil procured, (3) test hardware is constructed, (4) endurance testing is performed, (5) results are reported to the EPA, and (6) product is introduced to the market.

Steps 1-4 are time-consuming, expensive and Toyota’s product must enter market with oil that was used to report results to the EPA. Let’s set aside legal considerations and ask, what would it cost Toyota to answer your question for 6-8 other oil brands that are trying to catch up and maintain their market share? The cost is prohibitive and besides, Toyota is already working on step (1) for the next product cycle across several models.

Toyota spends 1.1 trillion Yen a year on R&D. That’s about 11 billion USD or about 10% of total global automotive R&D spending. Toyota’s global market share is 10%.

Each conventional and synthetic gear oil company has these choices, (1) lobby Toyota to get in at step 2 above, (2) perform laboratory testing to qualify against the latest GL-5 specification, (3) rely on reputation and marketing and/or (4) buy differentials/transfer cases and perform comprehensive endurance testing with various oil formulations. The latter is prohibitively expensive and time-consuming.

 

[DougR]

I would ask them if quality conventional or synthetic gear oil would provide equivalent or better protection against wear and damage than their specified oils.

I also have this answer to your question. Two major factors to consider are (1) the effect of temperature on oil life, and (2) moisture contamination by “breathing” or ingress. Yesterday, I drove my 4Runner 50 miles on a level freeway and measured temperatures on the transfer case (110 F) and differential (135 F). Ambient temperature was 65 F. Those are very low operating temperatures. It’s also very dry in Phoenix, so annual inspection of oil color should be sufficient as long as I don't immerse the differential in a flash flood. It appears to me that almost any GL-5 gear oil would easily endure 100,000 miles under these conditions.

ECGS says normal stock differential oil temperature range is 170-220 F. They recommend the following OCI in miles: 170F or less 100K miles, 200F-50K miles, 220F-25K miles … ECGS also recommends looking at cling ratio and cushioning. I haven’t figured out how to evaluate these. If the differential temperature doesn’t exceed 170F in the summer, I’ll schedule my next gear oil change at 100K miles.

 

[1000MPH]

Seal degradation was a thing in the early 2000’s. Funny that it was associated only with Toyota brand Synthetic gear oil. Now wouldn’t that be a hoot for those of us loyal to the “right” stuff.
Rear axle seal leaks caused by syn. gear oil | Toyota Tundra Forums

 

[delloro]

Toyota Corporation would have to perform a lot of time consuming expensive testing to answer your question. This would delay new product releases. Legal issues aside, there is no incentive for Toyota Corp to look at all the various oil formulations and grade them.

I think the overall R&D process goes something like this … (1) engineering proposes a new design or design improvements, (2) a lubrication specification is written and oil procured, (3) test hardware is constructed, (4) endurance testing is performed, (5) results are reported to the EPA, and (6) product is introduced to the market.

Steps 1-4 are time-consuming, expensive and Toyota’s product must enter market with oil that was used to report results to the EPA. Let’s set aside legal considerations and ask, what would it cost Toyota to answer your question for 6-8 other oil brands that are trying to catch up and maintain their market share? The cost is prohibitive and besides, Toyota is already working on step (1) for the next product cycle across several models.

Toyota spends 1.1 trillion Yen a year on R&D. That’s about 11 billion USD or about 10% of total global automotive R&D spending. Toyota’s global market share is 10%.

Each conventional and synthetic gear oil company has these choices, (1) lobby Toyota to get in at step 2 above, (2) perform laboratory testing to qualify against the latest GL-5 specification, (3) rely on reputation and marketing and/or (4) buy differentials/transfer cases and perform comprehensive endurance testing with various oil formulations. The latter is prohibitively expensive and time-consuming.

You didn't read the paper on xfer case oil on tacoma world?

Do you work for Toyota, or are you assuming a whole lot of things in your post? Not saying you can't be right, but what first-hand, specific facts to you have to support what you wrote?

Or is it your opinion, or a guess?

And just what "legal considerations" are you talking about? Specifically?

 

[DougR]

Seal degradation was a thing in the early 2000’s. Funny that it was associated only with Toyota brand Synthetic gear oil. Now wouldn’t that be a hoot for those of us loyal to the “right” stuff.
Rear axle seal leaks caused by syn. gear oil | Toyota Tundra Forums

"A note in DL003-03 states that "Toyota Genuine Synthetic Differential Gear Oil (P/N 00289–75140) CANNOT be used in 2000–2002 Tundra vehicles and 2001–2002 Sequoia vehicles. The rear axle oil seals are not compatible and will leak if synthetic differential gear oils are used in these vehicles."

"TSB DL002-03 titled REAR AXLE SEAL DESIGN CHANGE was issued. This TSB is applicable to ’01 – ’02 Sequoia, ’95 – ’02 Tacoma & ’00 – ’02 Tundra. The TSB states "The rear axle seal lip design has been changed from a flat face type to an angled face type."

I saw a post where one chemical additive in the oil formulation was incompatible with seal material.

There are many 100's of different parameters across several technical disciplines and vehicle models to consider during research and development of a driveline component. Mess up on one or two and issues like this arise.

 

[DougR]

Do you work for Toyota, or are you assuming a whole lot of things in your post? Not saying you can't be right, but what first-hand, specific facts to you have to support what you wrote?

What I wrote is based on ~40 years of working in gas turbine engine R&D including some work on failure analysis of products in the field. I often coordinated my analysis with multiple engineering disciplines including those responsible for gears, bearings, and lubrication. One of my responsibilities was to provide cooling to related engine hardware to help maximize lubricated component life.

 

[DougR]

And just what "legal considerations" are you talking about? Specifically?

What would happen if Toyota graded major oil brands and their various formulations into "recommended" or "not recommended" and didn't have comprehensive test data (100's of parameters collected over 100,000 miles of endurance testing) to back up their assessments? ... Lawsuits ... and even if they spent a small fortune testing all those oils, they would have to spend another small fortune defending their findings. Like any other business, they are focused on their products and the processes they use in R&D and manufacturing.

 

[delloro]

What I wrote is based on ~40 years of working in gas turbine engine R&D including some work on failure analysis of products in the field. I often coordinated my analysis with multiple engineering disciplines including those responsible for gears, bearings, and lubrication. One of my responsibilities was to provide cooling to related engine hardware to help maximize lubricated component life.

Awesome work, to be sure, but not Toyota, and not auto mfr lube spec work. So it is speculation, guessing, or both. Not saying you can't be right, but if you are, it was a guess.

 

[delloro]

What would happen if Toyota graded major oil brands and their various formulations into "recommended" or "not recommended" and didn't have comprehensive test data (100's of parameters collected over 100,000 miles of endurance testing) to back up their assessments? ... Lawsuits ... and even if they spent a small fortune testing all those oils, they would have to spend another small fortune defending their findings. Like any other business, they are focused on their products and the processes they use in R&D and manufacturing.

And you're a lawyer, too?

Nobody is asking anybody to "grade major oil brands."

Speculating again. What lawsuit are you familiar with where a mfr was required to "defend their findings"?

 

[ElectroBoy]

Too much energy being expended here.
Toyota Transfer Case Oil is still available.
Part number 08885-81080.

On sale now at McGeorge Toyota. $59.98 for one liter.

Transfer Gear Oil Lf 08885-81080 | McGeorge Toyota Parts

 

[DougR]

I would ask them if quality conventional or synthetic gear oil would provide equivalent or better protection against wear and damage than their specified oils.

Awesome work, to be sure, but not Toyota, and not auto mfr lube spec work. So it is speculation, guessing, or both. Not saying you can't be right, but if you are, it was a guess.

And you're a lawyer, too? Nobody is asking anybody to "grade major oil brands." Speculating again. What lawsuit are you familiar with where a mfr was required to "defend their findings"?

You wrote, "I would ask Toyota if quality conventional or synthetic gear oil would provide equivalent or better protection..." It appears to me that you are asking Toyota to endorse various oils. Are you or are you not asking Toyota to tell you what to use other than their oils? How is "quality" measured? And then you wrote, "Nobody is asking anybody to 'grade major oil brands'." Do you want me to distinguish between "grading", "endorsing", "recommended" and "approved"? I guess you're looking for a recommendation from Toyota regarding oils they haven't tested or used. Hmm, ... I think there are a few legal issues lurking somewhere in there.

I'm done with this circular run-around. It's like trying to catch a pig coated in gear oil.

 

[smeerun]

Too much energy being expended here.
Toyota Transfer Case Oil is still available.
Part number 08885-81080.

On sale now at McGeorge Toyota. $59.98 for one liter.

Transfer Gear Oil Lf 08885-81080 | McGeorge Toyota Parts

Save $2 - OEM Parts has it $57.92 per liter. :thumb:
Transfer Gear Oil LF 75W 08885-81080 | OEM Parts

They also have the Gear Oil for $26.04.
Differential Gear Oil LT GL-5 75W-85 (1 Liter) 08885-02506 | OEM Parts

 

[1000MPH]

That’s the best price I’ve seen but shipping ain’t cheap.
I just checked and it’s back to “available” at several of the dealers near me on the Toyota parts system.
Interesting.
I see list is $88.38. I browsed a few dealers in that system and saw prices from $61.11 to $97.22!!! (Inver Grove Toyota,MN)

 

[delloro]

You wrote, "I would ask Toyota if quality conventional or synthetic gear oil would provide equivalent or better protection..." It appears to me that you are asking Toyota to endorse various oils. Are you or are you not asking Toyota to tell you what to use other than their oils?

I am not.

How is "quality" measured?

Read the pdf here if you have not yet. Toyota knows what does and does not protect their xfer cases, and what protects them better. I presume, and would in fact bet money, that they have the same information on diffs. I would bet they know what commonly-available gear oils provide adequate protection, and it's not just the dealer fluid.

And then you wrote, "Nobody is asking anybody to 'grade major oil brands'."

You are correct, I did write that, and nobody is asking that (at least not here in this thread).

Do you want me to distinguish between "grading", "endorsing", "recommended" and "approved"?

I don't want you to do anything, actually, but "approve" would be useful and realistic.

I guess you're looking for a recommendation from Toyota regarding oils they haven't tested or used.

You guessed poorly. I am not.

Hmm, ... I think there are a few legal issues lurking somewhere in there.

There are always some legal issues lurking somewhere, so what? If you think there us something particular, or with identifiable merit, please do identify them with intelligible specificity. Otherwise, you may as well announce to the world that "teenagers eat a lot" or "water is wet." We already know these things.

Here are my underlying presumptions:

Their specified lube (75w-85) is a unique spec.

It was selected following research, which research provided information, including what worked and what did not.

Their baseline gear lube was either COTS or factory fluid.

The 75w-85 was selected because it provided something the baseline lube did not.

They could tell us what that was.

 

[ElectroBoy]

This debate has been going on for many years, and it’s not unique to Toyota. No OEM is going to tell you why they specify 75W-85 gear oil. Same for specifying 0W-20 engine oil. But the consensus believes it’s for squeezing out the most MPG for CAFE rules. Money talks.

Here’s another article about it:
Can 75W-90 Replace 75W-85 API GL-5 Gear Oil?

 

[delloro]

This debate has been going on for many years, and it’s not unique to Toyota. No OEM is going to tell you why they specify 75W-85 gear oil. Same for specifying 0W-20 engine oil. But the consensus believes it’s for squeezing out the most MPG for CAFE rules. Money talks.

Here’s another article about it:
Can 75W-90 Replace 75W-85 API GL-5 Gear Oil?

And how is the money talking here?

And why do you say "No OEM is going to tell you why they specify 75W-85 gear oil." Why not? Why can they not just tell us? If it's to save fuel, they can say so.

 

[ElectroBoy]

And how is the money talking here?

And why do you say "No OEM is going to tell you why they specify 75W-85 gear oil." Why not? Why can they not just tell us? If it's to save fuel, they can say so.

If OEMs don’t meet CAFE they pay fines. That’s $$.

People have been wondering, discussing on forums, arguing for years, asking car companies to please explain. Automotive journalists have written about it for years. Crickets from OEMs.

Why no answer? Read the article I linked above.

 

[DougR]

No OEM is going to tell you why they specify ...

Based on my experience working ~40 years at one particular aerospace company, all communication about products and services were the responsibility of legal, sales, public communications and a very few specific individuals authorized to communicate under specific conditions for a specified period of time while keeping a record of their transactions.

 

[1000MPH]

Based on my experience working ~40 years at one particular aerospace company, all communication about products and services were the responsibility of legal, sales, public communications and a very few specific individuals authorized to communicate under specific conditions for a specified period of time while keeping a record of their transactions.

Same here.

 

[delloro]

If OEMs don’t meet CAFE they pay fines. That’s $$.

Sure, no argument, but does CAFE actually mandate the mfr to mandate certain lubricants? I guessI will look when I have time.