3rd Gen Differential and Manual Transmission (6MT) Fluid Change

GREAT WRITE UP!!!

 

Blackstone results are in!

Here are some cliff notes/what I feel is going on/what I think Toyota has wrong - don't freak out, I'm an engineer too so I know what it's like for someone to give an opinion when they haven't spent time with the design. THAT SAID, Toyota is notorious for copy/paste errors in literature and just getting other details wrong here or there.

• Blackstone doesn't have a great handle on the baseline for our trucks. No fault of blackstone's, just that we have new trucks with new drivetrains and the samples probably haven't poured in.
• Blackstone probably isn't in the business of making strong claims, especially on OEM fluids (lawsuits have real consequences even for 3rd parties). I read between the lines a bit, but will try to talk to call and talk to a person sometime this week to confirm or deny my thoughts.
• In my opinion, Toyota's regular maintenance schedule is NOT ACCEPTABLE for these fluids. Many of you do much more with your trucks and in more severe conditions than me, but based on my understanding of these results I should be following closer to the severe service intervals rather than the regular ones (not counting the engine oil). This truck sees 90% pavement and 10% gravel or dirt forest service roads. Again, I do not abuse this truck; based on the language in the warranty and maintenance guide, I wouldn't assume the specific conditions apply to me.
• Use your own judgment. Looking at the warranty/maintenance guide in detail, the severe service replacement schedule seems to be more in-line with what I expect. Though I haven't tested it, I would assume the engine oil to be fine. 5k changes on synthetic oil is probably too often.
• I will be doing the diff fluid service again in 20k miles with more test samples. That will give me a better read on what the true service intervals SHOULD be for my truck and use conditions.
• I will be doing the manual transmission fluid service again in 20k miles, with more testing. I have a feeling I can probably extend to 30k intervals after that.
• I switched from OEM fluid. I'm glad I did. Based on my research, the fluid I used should have an extended service life as well. If I really wanted to be scientific about it, I would have used OEM fluids. Maybe someone else will, but frankly I feel better that I didn't (especially with their note on the MT fluid).

Keep in mind I did this fluid change at 10,500 miles. Here's a short version of what's on the reports since opening an attached PDF can suck sometimes on mobile:

Front Diff:

• Not as much metal as what was found in the rear diff
• Expected break-in elements
• Check back in 20k miles
• Compared to the universal averages the following were high: Chromium (by a lot), Iron (by a lot), Copper, Manganese, Boron (by a lot), Silicon (by a lot), Barium
• Insolubles % was high

Rear Diff:

• Excess metal (note was made regarding a comment I wrote on the sample slip)
• Can shoot for 20k miles on the next fill but 10k miles is fine...
• Compared to the universal averages (32.6k miles on fluid) the following were high: Chromium, Iron (by a lot), Copper (by a lot), Manganese, Potassium, Boron, Sodium

Manual Transmission:

• Oddity with oil viscosity and flashpoint (both read lower than what they should, but could have been for a few reasons)
• Expected break-in elements
• Compared to universal averages (18.4k miles on fluid) the following were high: Copper, Tin, Molybdenum, Nickel, Titanium, Potassium, Silicon (by a lot), Zinc, Barium

@Doggman - credit for calling this early on haha.

OA

 

thank you.

 

Cool. Thanks for reporting back. I just pulled a sample of motor oil to send off. First time changing after 6700 miles over about 6 months.

 

Really cool of you to do this and share with the group. Thank you!

 

Dood...Dawesome...said it once, I'll say it again...stick-worthy

Gracias for the follow up

 

Fascinating science here, thanks for the detailed information. I think it is safe to say ( and this goes for other trucks/vehicles as well) that the factory recommended service intervals are to be taken with a grain of salt. Not that they don't establish a good baseline of a maintainence schedule but we all use our trucks under varying conditions of severity, terrain, climate. Interested to hear some of the more scientifically inclined TW members chime in on these lab numbers especially the different types/ amount of residue in the used oil

 

I think I'm going to go ahead and send off a sample or 2 as well. It's only 28 bucks and it would be great to have more data points.

 

Thank you for the info!!!

 

Please explain. I don't understand Dannyblues

 

You can buy a pitch guage at a good auto store or maybe good hardware store if they still sell them. Mines 40 years old. Dannyblues

 

Different Spec Fluid, Toyota calls for 75w-85 and that was

$30 75w-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75w-90.

 

I agree. When you buy oil from Toyota you get their OEM oil manufactured by Mobil 1. Identical to Mobil 1 ?? Who knows. But in the shop each dealer buys oil in bulk cans. Who knows what oil that is??? Is it identical to the OEM oil in the bottles marked Toyota ? Dannyblues

 

Whatever they get cheapest...

 

Really I thought it was 75/90 OEM fluid?? I asked the shop foreman to change my transmission fluid after they remedied the manual transmission gets stuck in gear problem with the TSB-0088-16 bulletin I had to locate and inform them about myself!! I even dragged in the district field service rep and another big wig from Toyota corporation because I made so much noise about the danger of the stuck in gear shifter.
The foreman was ordered to repair the shifter problem with parts and directions from that TSB. And drain and filter my tranny fluid through a painters fine paper cone filter. I was told no metal fragments not even wear in metal fuzz.

They were also ordered to refill my manual tranny with fresh fluid. When I asked the foreman what fluid it was he told me 75/90 w gear oil.

So if what you say is true then I got either the wrong weight gear oil refilled or it was filled from a Toyota drum of the correct fluid by the mechanic who actually did the job and the foreman was once again wrong with what he told me which was 75/90 gear oil. Thanks for that information. Dannyblues

 

The Diffs Spec at 75w-85.

 

I believe that. I believe the dealer gets whatever is cheaper. Maybe buys at Walmart. Who's to know. When the components fail either you pay because you are out of warranty or they have Toyota pay them at the warranty rate. Either way they make money. I believe dealer shops are more uncaring and apathetic or inept and are more interested in a fast repair turnover of vehicle repairs each day than any quality work done by a good local shop who is trying like hell to stay in business at a profit and keep and grow its customer base. I'm still under the 36,000 mile original warranty so I'm kind of married to the dealer. I know if I keep records and receipts I can do the work myself or go to a private shop. But thus far almost all work done has been free because the dealer shop screwed me up so many times. Dannyblues. Just my 2 cents.

 

What can I say but thank you I'm sure from many of us! What tranny fluid did you use??? Can't find your great post on that. Dannyblues

 

I have all the fluids I used in the first post of this thread. I used Amsoil

$30 75w-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75w-90 MT fluid.

OA

 

Just curious why you didn't use severe gear in the trans?