Gear Oil Question

[Climb14er]

Not sure if it applies to Toyota axles, but lots of axle makers including Dana which is a giant in the axle industry recommend that you DO NOT use synthetic oils in the differentials.

Syn. oils are debatable in engines with lots of friction parts... but for a gearset you don't really want that "slippery" nature of the oil. You just want to keep things cool and lubed and syn. oils over time can actually cause more wear and shorter life.

I once had a Jeep with a Chrysler Corporate 8.25 axle which was regarded as a very bulletproof design. I put syn. fluid in it and immediately had chattering issues and noise. Drained it and put $3/quart walmart fluid back in and it ran smooth as butter from then on.

Now days the only thing I buy is the "cheap" axle fluid. Change it when needed and don't worry about it. It's a simple gearset...not a high tech engine.

Doesn't apply to Toyota!

Been running Redline and before that Mobil Synthetic gear lube in my Toyota pickups for many years.

Also Redline MTL in my older five speed manual tranny.

I run Redline's Shockproof Heavy in my Harley Road King Classic's tranny and the shifting is very smooth. Also their MTL in the Harley Primary and Redline's 20W-50 in the Harley 103 engine.

There are some very good gear and tranny lubes on the market.

Redline gets my money! Their quality is IMHO, unsurpassed. :cheers:

 

[LobstaMobsta]

Replacing the Gear Oil. Want to go full Synthetic. Local shops don't have Synthetic 80w-90.

They do have Royal Purple 75w-90 full synthetic.

Anyone run that weight? Any issue with it being "too" light for the winter? As we move into summer, I am not concerned right now; as the temp will keep it at the 90 viscosity, but is the 75w too light?

Local shops don't carry synthetic? Wow they must be stuck in 2000! All 2000+ gm vehicles require synthetic gear oil. Even usually stamped on the diff housing

 

[Mr. Baseball]

I made a mistake in earlier post. I was told the 75w90 was synthetic by parts employee. They actually used a mineral based 75w90, part number 08885-02106. Labeled as Toyota Gear Oil Super GL-5 75w90. This is what i was told by service. Sorry about the misinformation. I had front and rear diffs and transfer case serviced in a 2004 4Runner.

Just want to add this is what I was told. Receipt just says "goil". Not sure who to believe but I looked up the part # and found it at jayteclubricants.com. Why is Toyota gear oil so secretive? I trust all the info I've read here and will be using Amsoil or Redline, perhaps Mobile 1 sold at pep boys across the street. Thank you everyone.

 

[4RunnerFan]

If vehicle is 4WD, my '08 manual says weight depends on which case you're working on:
Rear diff: 75W-90
Front diff: 80W-90
Xfer case: 75W-90

 

[Mr. Baseball]

Maybe since my '04 takes 75w90 for transfer and 80w90 for front and rear, according to manual, they used 2 different gear oils. I was told all conventional, synthetics will cause leaks because I am nearing 100k and don't know what previous owner used. I only know he said it was changed at 30k intervals (got it with 63k). I had changes done at 93k.

Any thoughts on switching to quality synthetic now at 93k or next change at 120k? TSB says synthetic 75w85 ok for 2003-2007 4Runners, at least for differentials, not sure about x-fer case. Thank you.

 

[Mike07SE]

Just had new diffs put in that I got from ECGS. Not sure if the ARB front and TrueTrac rear is the deciding factor, but they were insistent that I use 75-140, more specifically non-synthetic. Their brand of choice was also Lucas Gear Oil.

 

[Ali0227]

I want to post a relevant story about 4Runners and gear oil. I have learned a lot from this website and I want to pass my experience on to others.

I own a ’98 4Runner (3.4L-V6, 4WD) I bought used in 2008. It had 134,000 miles on it and the CarFax listed several owners, the first of which, when it was new, as a vehicle leasing company. That should have been my first warning sign.

At 137,950 miles, I had the front and rear differential and the transfer case oils all changed. The mechanic that did the work told me all the oils looked as though they hadn’t been changed since the vehicle was new. He specifically said the rear differential’s oil looked bad. Warning sign number 2.

At the 177,370 mark, I started to hear a low hum at highway speeds. I thought the sound was coming from the front end so I specifically took it to a Toyota dealer to diagnosis the sound but they found nothing. Warning sign number 3.

At 180,000 miles, I changed the oils in the two differentials and the transfer case again, but this time I did the work myself and I researched the exact oil to use in all 3. And just as every other Toyota customer has found, I could not find a single weight oil (Toyota specified 90W oil in the rear diff on the ‘98 4Runner).

Like everyone else here, I got on the internet and searched, and saw where other 4Runner users were using multi-weight oil but there was always a debate on what particular choice of multi-weight oil. After lots of research and reading of posts (several of which were on this website), I finally chose Mobil 1 Synthetic 75W-90 gear oil. The 75W-90 weight oil was exactly what Toyota called for in both the front differential and the transfer case, but I was a little hesitant to use it in the rear differential. I finally took the plunge and put it in all 3.

Over time the hum sound got so loud I wore ear plugs when I drove at highway speeds for long distances. At 193,300 miles I took it to another mechanic and he said it was the carrier bearing of the rear differential. In mechanic’s speak it’s called it the “3rd member” with the 3rd member being the rear differential.

I had him install a Jasper Engine remanufactured rear differential which came with a 3 year/100,000 miles warranty. The mechanic told me to use the exact oil that Toyota recommended (i.e. SAE 90W) or it would void the Jasper warranty.

Remembering that I had had trouble locating 90W oil before, I asked what oil did he put in the differential when he installed it? He said Jasper ships the oil they want used in the differential so he doesn’t have to choose.
I then asked if the 75W-90 Mobil 1 gear oil could have caused the bearing to go out but he wouldn’t give a specific answer one way or another. When I asked if M1 75W-90 oil would be OK in the remanufactured differential, he again said “use exactly what the manufacturer recommends” so he was no help at all.

I called Jasper and they said the same thing as the mechanic: use SAE 90W oil. The customer service representative even looked up the spec.’s on the vehicle while I was on the phone with him. When I told him you can’t find single weight oil, he offered no compromise but simply said: “Jasper recommends you follow the manufacturer’s recommendations.” The reason I was so particular on the weight oil to use is I was concerned that use of the M1 75W-90 may have caused the rear differential to fail and I wanted to abide by Jasper’s warranty.

After the Jasper recommended 5,000 mile break-in period , I began to search for 90W oil and again couldn’t find any. I even visited a Toyota dealer and inquired about purchasing gear oil and was told they don’t sell it directly to the customer.

I got on the Toyota website and emailed their customer service regarding what oil to use. They emailed back and directed me to visit another Toyota dealer. I visited a 2nd dealer and was told the same thing as the first dealer (they don’t sell in quantities to the customer), but the 2nd dealer did say he thought M1 75W-90 would be fine for the differential.

I called a 3rd Toyota dealer and he told me: “of course you can’t find single weight oil that’s why we use multi-weight oil!” He even went so far to say they use 80W-90 or 85W-90 weight (he couldn’t remember which it was—he said he would have to look at the label on the oil drum). I thanked him and told him he had told me more than the other 2 dealers had on what they use in the service department.

I went to Advance Auto Parts and told their counter salesmen my story. One said he was a former Toyota mechanic and he confirmed they use multi-grade oil. He and another salesman both agreed that the M1 oil I used did not cause the rear differential to fail but it was probably due to the clean oil flushing out all the sludge from inside the bearing that had accumulated due to the lack of oil changes from the previous owners.

One salesman even said his wife’s used car is doing the same thing—he changed the rear differential oil, the oil looked very bad and had not been serviced regularly, and he now hears a noise coming from it. He said it probably won’t be long and it will go out too. After discussing it with them, I finally decided on Lucas Oil 80W-90 gear oil.

Armed with this new information, I contemplated Toyota’s first email response where I got the run around and finally decided to email them back that I was going to use 80W-90 since that was the closest I could find to 90W. I also stated I was going to send a CC of my email to Jasper with the idea I could prove I did my part as an owner/operator to see I used the correct oil when and if I had to use Jasper’s warranty.

I immediately got a reply within 2 hours or so (versus 2 days for my first email) and from someone different than my first reply. This entire email is below:

Thank you for contacting Toyota Motor Sales, U.S.A., Inc.

We are sorry for the difficulty you have experienced with locating the appropriate weight oil for the rear differential in your 1998 4Runner.

We do realize that single weight oils are no longer available, thus, Toyota Motor Sales, U.S.A., Inc. recommends and approves the use of multi weight oils such as 85W/90, as when operated they reach the 90W rating at normal operating temperatures.

Also, since Jasper is not a Toyota company, we may not advise on their warranty policies. We would recommend contacting them directly regarding any warranty questions.

We truly apologize for any inconvenience this matter has caused you.

If you have any other questions, please feel free to contact us via email by using the following link, Toyota Help or by calling 800-331-4331. We are available from 5 AM to 6 PM, Pacific Time, Monday through Friday and from 7 AM to 4 PM on Saturday.

Sincerely,
Anita Mouton

I found it rather amusing that Ms. Mouton clearly admitted that “We do realize that single weight oils are no longer available....” and she also gave a recommendation of 85W/90 gear oil. What I fail to understand is why this was not told to me in their first reply to my original email.

I wish now I had used the M1 75W-90 oil as I received Ms. Mouton’s email after I had already installed the Lucas 80W-90 oil. I am now giving serious thought to switching back to M1 75W-90 as I feel from her reply it would be sufficient. Like many of you here, I am a big fan of synthetic oils.

I hope this story can be of some good use for other 4Runner owners.

Am I reading your post incorrectly that you had problems with the rear diff after using the synthetic?

 

[Ali0227]

I want to post a relevant story about 4Runners and gear oil. I have learned a lot from this website and I want to pass my experience on to others.

I own a ’98 4Runner (3.4L-V6, 4WD) I bought used in 2008. It had 134,000 miles on it and the CarFax listed several owners, the first of which, when it was new, as a vehicle leasing company. That should have been my first warning sign.

At 137,950 miles, I had the front and rear differential and the transfer case oils all changed. The mechanic that did the work told me all the oils looked as though they hadn’t been changed since the vehicle was new. He specifically said the rear differential’s oil looked bad. Warning sign number 2.

At the 177,370 mark, I started to hear a low hum at highway speeds. I thought the sound was coming from the front end so I specifically took it to a Toyota dealer to diagnosis the sound but they found nothing. Warning sign number 3.

At 180,000 miles, I changed the oils in the two differentials and the transfer case again, but this time I did the work myself and I researched the exact oil to use in all 3. And just as every other Toyota customer has found, I could not find a single weight oil (Toyota specified 90W oil in the rear diff on the ‘98 4Runner).

Like everyone else here, I got on the internet and searched, and saw where other 4Runner users were using multi-weight oil but there was always a debate on what particular choice of multi-weight oil. After lots of research and reading of posts (several of which were on this website), I finally chose Mobil 1 Synthetic 75W-90 gear oil. The 75W-90 weight oil was exactly what Toyota called for in both the front differential and the transfer case, but I was a little hesitant to use it in the rear differential. I finally took the plunge and put it in all 3.

Over time the hum sound got so loud I wore ear plugs when I drove at highway speeds for long distances. At 193,300 miles I took it to another mechanic and he said it was the carrier bearing of the rear differential. In mechanic’s speak it’s called it the “3rd member” with the 3rd member being the rear differential.

I had him install a Jasper Engine remanufactured rear differential which came with a 3 year/100,000 miles warranty. The mechanic told me to use the exact oil that Toyota recommended (i.e. SAE 90W) or it would void the Jasper warranty.

Remembering that I had had trouble locating 90W oil before, I asked what oil did he put in the differential when he installed it? He said Jasper ships the oil they want used in the differential so he doesn’t have to choose.
I then asked if the 75W-90 Mobil 1 gear oil could have caused the bearing to go out but he wouldn’t give a specific answer one way or another. When I asked if M1 75W-90 oil would be OK in the remanufactured differential, he again said “use exactly what the manufacturer recommends” so he was no help at all.

I called Jasper and they said the same thing as the mechanic: use SAE 90W oil. The customer service representative even looked up the spec.’s on the vehicle while I was on the phone with him. When I told him you can’t find single weight oil, he offered no compromise but simply said: “Jasper recommends you follow the manufacturer’s recommendations.” The reason I was so particular on the weight oil to use is I was concerned that use of the M1 75W-90 may have caused the rear differential to fail and I wanted to abide by Jasper’s warranty.

After the Jasper recommended 5,000 mile break-in period , I began to search for 90W oil and again couldn’t find any. I even visited a Toyota dealer and inquired about purchasing gear oil and was told they don’t sell it directly to the customer.

I got on the Toyota website and emailed their customer service regarding what oil to use. They emailed back and directed me to visit another Toyota dealer. I visited a 2nd dealer and was told the same thing as the first dealer (they don’t sell in quantities to the customer), but the 2nd dealer did say he thought M1 75W-90 would be fine for the differential.

I called a 3rd Toyota dealer and he told me: “of course you can’t find single weight oil that’s why we use multi-weight oil!” He even went so far to say they use 80W-90 or 85W-90 weight (he couldn’t remember which it was—he said he would have to look at the label on the oil drum). I thanked him and told him he had told me more than the other 2 dealers had on what they use in the service department.

I went to Advance Auto Parts and told their counter salesmen my story. One said he was a former Toyota mechanic and he confirmed they use multi-grade oil. He and another salesman both agreed that the M1 oil I used did not cause the rear differential to fail but it was probably due to the clean oil flushing out all the sludge from inside the bearing that had accumulated due to the lack of oil changes from the previous owners.

One salesman even said his wife’s used car is doing the same thing—he changed the rear differential oil, the oil looked very bad and had not been serviced regularly, and he now hears a noise coming from it. He said it probably won’t be long and it will go out too. After discussing it with them, I finally decided on Lucas Oil 80W-90 gear oil.

Armed with this new information, I contemplated Toyota’s first email response where I got the run around and finally decided to email them back that I was going to use 80W-90 since that was the closest I could find to 90W. I also stated I was going to send a CC of my email to Jasper with the idea I could prove I did my part as an owner/operator to see I used the correct oil when and if I had to use Jasper’s warranty.

I immediately got a reply within 2 hours or so (versus 2 days for my first email) and from someone different than my first reply. This entire email is below:

Thank you for contacting Toyota Motor Sales, U.S.A., Inc.

We are sorry for the difficulty you have experienced with locating the appropriate weight oil for the rear differential in your 1998 4Runner.

We do realize that single weight oils are no longer available, thus, Toyota Motor Sales, U.S.A., Inc. recommends and approves the use of multi weight oils such as 85W/90, as when operated they reach the 90W rating at normal operating temperatures.

Also, since Jasper is not a Toyota company, we may not advise on their warranty policies. We would recommend contacting them directly regarding any warranty questions.

We truly apologize for any inconvenience this matter has caused you.

If you have any other questions, please feel free to contact us via email by using the following link, Toyota Help or by calling 800-331-4331. We are available from 5 AM to 6 PM, Pacific Time, Monday through Friday and from 7 AM to 4 PM on Saturday.

Sincerely,
Anita Mouton

I found it rather amusing that Ms. Mouton clearly admitted that “We do realize that single weight oils are no longer available....” and she also gave a recommendation of 85W/90 gear oil. What I fail to understand is why this was not told to me in their first reply to my original email.

I wish now I had used the M1 75W-90 oil as I received Ms. Mouton’s email after I had already installed the Lucas 80W-90 oil. I am now giving serious thought to switching back to M1 75W-90 as I feel from her reply it would be sufficient. Like many of you here, I am a big fan of synthetic oils.

I hope this story can be of some good use for other 4Runner owners.

Am I reading your post incorrectly that you had problems with the rear diff after using the synthetic?

 

[Drcoffee]

I have heard before that Mobil1 75w90 is actually thinner than its rating and most likely leak past the axle seals. I will use either valvoline synthetic 75w90 or Amsoil severe gear. If you live in a southern region where temps are 90+ you can also use 75w140 which would give better protection, but slightly less mpg.

 

[aemravan]

ECGS recommended the 85W140 non synthetic oil, that's what i've been running with no issues.

It is thicker than the synthetic oil and is able to dissipate heat much better. It's also a super cost effective alternative to the synthetic oil alternatives. I've been using it for the past 2 years now.

 

[rdruss]

If I lived in a warm weather area I would follow EGS advice, but I live in Chicago area so have Amsoil 75W90 HD in front/rear/T-case. Don't expect any problems.

 

[bob919]

Yes, I think I did have issues with the original, OEM differential after putting in the synthetic oil that first time. As my post states above, I think that first original oil change did flush out all the contaminants and the carrier bearing went out. Again, just an opinion.

But the remanufactured differential is still working fine with 315k miles on the vehicle, even after going back to Mobil 1 synthetic after using the Lucas oil for that 1 interval of time that I mentioned in my post above.

As of today (August 2023), I'm still using Mobil 1 synthetic gear oil and haven't had any issues. I changed the oil out at 251k miles and again at 265k miles. I meant to change it again at 280k and stay on that 15k interval but haven't done it (life hit and I have been busy). I've seen different mileage intervals recommended for differential oil changes and thought I saw 30k as one recommendation so with my 4Runner right now at 315k, if that last time I did it was 280k, then 35k for synthetic oil would maybe be fine.

Anyone with any thoughts chime in. Hope this helps you Ali0227.