Differential Fluid Advice

[nc211]

Hey guys, I think it is time for the rear differential fluid to be changed. I've never actually done this, but it doesn't look that hard. It's just drain and fill, right? Any suggestions on oils to use? I know the oem stuff is oem stuff, but was wondering if there were any synthetic blends on the shelf that might be better. I'm very impressed with the mobile one 5w30 synthetic in my engine now, and think synthetic gear oil might be good too. I saw something from Penzoil that was synthetic and the right weight the other day. But, outside of oem stuff, I have learned to ask those who know, before doing anything on my own.

Thanks guys,

[alsalih]

I also use synthetic for my engine, however when it comes to diff's my personal experience is to stick with standard lubricant 80-90. The lower viscosity of the synthetic will give you a louder gear noise. I have had to replace diff bearings on two different vehicles shortly after switching (30K miles) to synthetic Mobil gear fluid. Use synthetic only if it's called out from the factory as some vehicles now have.

Yes, very easy drain and fill and you don't really have to replace the washers they can be reused several times without any leaks. Torque the allen bolts to 39 ft-lbs.

[dcfish]

I also use synthetic for my engine, however when it comes to diff's my personal experience is to stick with standard lubricant 80-90. The lower viscosity of the synthetic will give you a louder gear noise. I have had to replace diff bearings on two different vehicles shortly after switching (30K miles) to synthetic Mobil gear fluid. Use synthetic only if it's called out from the factory as some vehicles now have. 

Yes, very easy drain and fill and you don't really have to replace the washers they can be reused several times without any leaks. Torque the allen bolts to 39 ft-lbs.

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Use 80-90 gear oil - non synthetic. ;)

[blake918]

NC, Roy (Agent 99/99LSguy) put together a fine rear differential tutorial...everything you need to know + more!

DIFFERENTIAL_FLUID_CHANGE.doc

[nc211]

Thanks guys! Much appreciate the feedback. I think I'll stick with the non-synthetic stuff. Any recommendations on manufacturers? As my tag gives away, I live in North Carolina, but sometimes it gets pretty darn cold in the winter, no sub zero stuff, but close sometimes. I think I'll go with the 80-90w set up instead of the straight 90w. Interesting on the gear oil pump, I was wondering about how to get that stuff into the differential.

Blake, know any good threads on drain n' fill for the transmission fluid as well? It's looking like my weekend of fishing at the beach might be down the tubes thanks to tropical storm Irene heading our way. So, good time to do some maintanence on the road warrior. I'll be picking up some tranny fluid from the dealer later today, won't even think about anything but oem on that stuff. If it's bad, I want Lexus on the hook for it, not Napa.

[blake918]

I like that..."Road Warrior!" B) Draining the trans pan is just one bolt (I want to say 14mm. I should know this since I've done it probably 10x. lol)...it's stupid easy! 2 quarts of T-IV is all I need when I do a pan drain. The mark-up on T-IV is incredible. I usually pay about $12 for 2 quarts after tax at a local Toyota dealer. My neighbor across the street works in the parts dept of that Toyota dealer, so I got his employee discount...2 quarts for just over $5! :o You'll need a long and very skinny funnel to refill the atf through the dipstick. ;)

[nc211]

I just called the lexus dealership, and they too sell them at $5.34 a quart! Go figure that one? My car is over there right now getting the oil pan gasket leak fixed. They replaced the lower pan a month or so ago due to a stripped out threading that walmart did. Apparently they did not do a good job, because I was just told Monday when getting my oil changed, that it's leaking pretty badly. Some new tech is using my car as a learning experience, not too happy about that. Everything this guy has done, has needed to be redone. But anyway, got 2 quarts of the stuff, think that should be good to go!

[monarch]

Both Toyota & Nissan now have their own 75W-140 GL-5 synthetic gear oil that's ideal for the differential http://www.saber.net/~monarch/fluids.jpg This oil is substantially thicker than Mobil 1 75W-90 gear oil so there isn't the gear noise problem.

Toyota dealer mark up on fluids varies widely. For example, Type T-IV has a Toyota suggested retail price of about $3.75 a quart, but some dealers offer a 25% discount off retail so you can get it for around $2.50 a quart. At the other extreme, some Toyota dealers charge *above* retail @ $5-6 a quart. Bear in mind corporate Toyota isn't to blame for the outrageous markups some dealers charge - it's the opportunistic Americans who own and run the Toyota dealerships.

Also bear in mind Toyota dealers can buy aftermarket fluids & lubes more cheaply than they can buy genuine Toyota fluids. So here again the $profit$ motivated Americans who run Toyota dealerships will commonly service your Toyota or Lexus using aftermarket fluids and lubes instead of genuine Toyota stuff.

Savvy Toyota / Lexus owners will just accept and work around this situation and buy genuine Toyota fluids from a discount dealer. That way they get the best of both worlds; i.e. a reasonable price for top quality fluids & lubes.

[sha4000]

i have some of that mobile1 75w-90 do you guys suggest that i dont use it b/c i like a quiet car

[morg96ls400]

Hey nc did you get around to replacing your differential mounting cushions? Was wondering how that went/how long it took you. Was thinking of replacing mine but it looks like a ton of work (removing exhaust / prop shaft / differential), also if you did, did it solve your transmission "clunk"? Mine still occurs but sporadically. Let me know! thanks

[nc211]

Hey morg, yeah I did get the differential bushing changed out, no more clunk except the usual lurch when shifting into D when the engine is cold "high idle". It smoothed it out a bit. I didn't do it myself though. When I started the whole process of changing everything, I made it past all the front stuff, but was too whipped to take on the rear stuff. I paid a local indi $600 to change out the rear control arms, strut rods, struts and those bushings. He did say that he had to remove the differential to get them out. I tried a few times to do this myself, but had no luck. You're right, it does look like a lot of work, quite a few bolts to get that diff off. You don't have to remove the drive shaft though, just unhook it from the diff "3 bolts." But I think you have to remove the axles from the diff too, and that looked a little much. Especially if you're doing this on your back. You really need a full lift to do this stuff w/o killing your back. Those bolts I think are set at like 85 lbs of torque. That made it impossible for me to get them off at the angle of attack you have on the ground. I would think if you took them to an indi, and gave him a C note, you'd be good. It did make a difference, and was worth it. But it did not fix the lurch completely. I think the drive shaft's flex couplings play a bit part in that problem as well. I haven't tackled that yet. I'm still trying to get the wheels all dialed in correctly from the major suspension overhaul. I think I shocked the car so badly that it needs an actual dial reading on things.

[morg96ls400]

Hey im glad you got that fixed. Sounds like I will be takin mine in to get them changed too, was quoted about 6-7 hrs of labor, thanks for the info!

[nc211]

No problem amigo. It shouldn't take that long in all honesty. They did all that repair work on mine in 8 hours.

[nc211]

Well, the fluids were changed. It was easy as pie. Sure am glad I read that tutorial before I did the rear differential. Getting the fill plug out first is crucial! That thing was in there pretty good! The tranny fluid was "stupid easy" When I drained the differential fluid first, I thought "that doesn't look that bad". It had a dark brown look. But, when I opened up the new stuff, then I realized how nasty that stuff really was! The new stuff is a light tan color "Valvoline 80-90w". Much smoother feel. The tranny fluid coming out was a super dark maroon color. I saw some red in it, thought "that doesn't look too bad either". But, as I poored in the new Toyota stuff, I realized how nasty it was as well! The new stuff is bright red. The old stuff was dark dark maroon, if not close to black. The car shifts a lot smoother now! Due to the freakin' death heat down here, I did not attempt the air intake cleaning. Just too damn hot!

[PK_Lex]

The lexus dealer near me doesn't carry gear lube and the guy wan't helpful at all to tell me what type I need.

Toyota dealer carries the synthetic kind. I asked them if they carry non-synthetic, he asked me that they carry different types and if my car (94 LS) has limited slip differential?? That threw me off and I didn't really knew what I really need so I came back.

If someone know what exactly goes in there, please let me know so I can ask for that type.

Thanks.

[nc211]

PK, I used the Valvoline 80-90w / gl 5 stuff. I have not a clue what gl 5 is, but the manual called for it. Mine was normal stuff, not synthetic. I decided to stick with the oem spec of original date, and went with non-synthetic. You can get this stuff at autozone for like $5 a quart. You'll need 2 of them, as it will take about 1.4 quarts. Also, a pump of some sort is REQUIRED to the new stuff in there. I bought one that looks like a caulking gun type. You put the plastic hose into the new bottle, pull back on the handle which fills it up. Then put the plastic hose into the top fill hole on the differential and push the handle back down to release the oil. It was super simple. A little tight under there, but super simple. Remeber, make sure you loosen up the fill plug FIRST to make sure you can fill it. My Lexus dealership didn't sell this stuff either, they have just big oil drums of it and use thier auto injector to fill the car.

[nc211]

Hey Morg, I did the transmission fluid drain a couple weeks ago while doing the rear differential oil. It was super easy, and I have noticed a much smoother transmission becuase of it. It drained 2 quarts, and I replaced it with oem tranny fluid. The fluid was dark dark maroon, almost black. The new stuff is alabama red, and did reduce the lurching a bit. Unfortunetly, the drain and fill method only gets out 2 of the 7 or so quarts "or so I hear". I think with the combinatin of the new diff bushings and the eventual replacement of all tranny fluid, it just might fix it.

[PK_Lex]

Thanks for the info and the tip. As much as it seems tempting to use the Toyota synthetic, I think I'll stick with OEM specs too.

[ko90ls]

yeah i hate when the tranny lurches and pulls. the who sold me my ls told me he had just changed it and the filter... WRONG. just outta curiousity i did it my self and also noticed a dark dark maroon color. almost made me sick. anyways you can add a partial tranny flush just go to lexls.com and do a flush with a gallon milk carton so you can measure when 4qts come out (3.8l maybe) and add accordingly. too bad for me just went to change the fulid again and stripped the nut :cries: oh well more new stuff :chairshot:

[Sung Park]

Hey guys, I'm a newbie here. I have some questions for LS owners.

How often do you change tranny/differential fluids? Every 30,000, or 60,000 miles?

Also, changing differential fluids, how do guys crawl under without lifting a vehicle? I guess I can jack up the rear end, but then it would not be in level any more. If you could teach me some tricks, I would really appreciate it.

One thing I don't like about my LS is that no matter how careful using jack stands (make sure they they are in between notches), I end up bending the frame. Am I doing something wrong?

Thank you.

[nc211]

Dang, now you know you've been around here too long when you're pulling up your own threads, from 2005.

We'll see what the synthetic fluids do to the differential, as I just replaced mine with the 80-90 synthetic valvoline last night. I do feel a smoother power delivery this morning, and less resistance. I decided to replace the fluid because since this original posting, I've put on probably 30k miles, and the differential had been removed from the car twice "to replace the mounts, and the drive shaft". I was not sure if the shop had replaced the fluids, or spilled any. I had a suprise last night to find that they had done both! The fluid that came out of the differential looked brand spankin' new! Looked exactly like the new stuff I was putting in, which was a huge shock to me! The magnetic drain plug was dirty, so I knew someone had replaced it. Now this is what I don't understand. The last time this could of happened was over the summer, with the conclusion of the wobble thread, but the fluid still looked brand new. HOWEVER, I was shocked to find that it was only half full!! I measured it as it drained into my clear plastic bottle. I even jacked up the driver's side to help assist it to pour out the drain hole....it was about 7/8th of a liter. The differential calls for 1.2 liters. There are no signs of leaks, none at all. I'm not sure what happened, or who made the error, but I was noticing a crabbing sensation in the rear of the car when going slowly, and a slight drooning noise at speeds of 50mph. That has stopped. No crabbing this morning "other than me complaining about coming to work", and no drooning noises.

So, we'll see how this synthetic stuff holds up... I'll update again later on.

[nc211]

The car is extremely smooth, and I've noticed that when I let off the gas, it coasts 10x's better, no feeling of pulling something behind it. It's also extremely quiet back there, no noises whatsoever. So far, the synthetic oil is spectacular. No signs of leaks from the shaft seals. I've also noticed the engine seems to be quieter too, like it's not straining at all. I wouldn't think gear oil in the differential would make a hoot of difference in the engine's performance, but I can honestly say, it feels better, and is definetly acting less strained.

[dcfish]

The car is extremely smooth, and I've noticed that when I let off the gas, it coasts 10x's better, no feeling of pulling something behind it. It's also extremely quiet back there, no noises whatsoever. So far, the synthetic oil is spectacular. No signs of leaks from the shaft seals. I've also noticed the engine seems to be quieter too, like it's not straining at all. I wouldn't think gear oil in the differential would make a hoot of difference in the engine's performance, but I can honestly say, it feels better, and is definetly acting less strained.

nc211, How do ? I changed the diffy fluid in the gs last year to synthetic and I also could feel/hear the difference, I have decided to change it out every 15k, If for nothing else it is a "feel good thing" and another confidence builder. ;)

[nc211]

Do well, inspector... :whistles: ...

I really wasn't expecting anything different with the synthetic gear oil, at all. I was just replacing it because I had a nagging feeling one of the mechanic's who changed the differential supports, or drive shaft, might have spilled some, or didn't refill it to proper levels. Just bugged me. This has turned out to be a nice little suprise, that's for sure.

[nc211]

As far as I'm concerned, everything but the tranny fluid is going to be synthetic from now on. The improvements of this gear oil has me convinced, synthetic is great stuff! I've got synthetic in the brake fluid, and it's an improvement. I'm going to flush the steering fluid soon and replace it with synthetic as well. Anyone know if they make synthetic coolant? I need a flush soon anyway.