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Thick, black, and nasty rear differential oil

6K views 12 replies 7 participants last post by  vanib 
#1 ·
I bought my 2008 Rav4 with the 2.4 a couple of months ago. I changed the rear differential fluid a couple of weekends ago. I would have sworn it was a rear wheel drive, the fluid was thick, black, and nasty. The previous owners must have used the 4 wheel a lot, but there was not a trailer hitch, nor were the frame bolts where it would have bolted up disturbed. They looked factory. Anyway, I did the front differential yesterday. I drove for 10 miles before draining it, so the fluid was about the right consistency for hot gear oil. However, it had a red tint to it. Does anyone know if Toyota dealership gear oil has a red tint? I've never used Redline, so does it? It almost looked as if a bit of tranny fluid had been mixed with it. Any ideas? I replaced it with Lucas 80w-90. The manual recommends straight 90 conv.,or 75w-90 synthetic. ( same as the Haynes book) Are any of the synthetics reddish? I've never used any so I have no idea. I'm just trying to figure out where the red tint came from. I've used many different brands of gear oil over the years, but they have all been about the same color..don't even have a name for it, just gear oil color! Thanks.
 
#2 ·
So, now I'm curious. I'm sort of new to this technical computer stuff. With all the people that have seen my question, does nobody have an answer or comment, or did I post it wrong? Did I post so nobody can reply? Is there a certain protocol I didn't follow? Thanks again.
 
#4 ·
It's like writing a newspaper article. You grab the readers attention with the headline. I changed your "headline" to something a little more descriptive.
 
#3 ·
gear oil is usually light brown to my knowledge, did you check the atf fluid's color, is it still red? do you have a picture of the oil that came out? mine was black when it came out.
 
#5 ·
almina said:
... I did the front differential yesterday. I drove for 10 miles before draining it, so the fluid was about the right consistency for hot gear oil. However, it had a red tint to it. Does anyone know if Toyota dealership gear oil has a red tint? I've never used Redline, so does it? It almost looked as if a bit of tranny fluid had been mixed with it...

Just so you know, the front diff you mentioned is co-located with the transmission, and bathed in tranny fluid. You must be referring to the transfer case, which is nearby but a separate unit.

In regards to you question, I'm not sure if any gear oils are reddish tint. Octane has a good suggestion to compare the consistency and color of the ATF to determine if previous owner put the wrong stuff in transfer case.
 
#6 ·
Yeah, I goofed on my terminology, sorry about that. The atf fluid that I drained from the tranny was in fact atf. It did not seem to have been mixed with any gear oil, although it was quite dark. It's entirely possible that a previous owner did put the wrong (atf) fluid in the transfer case, and then someone else caught that, I have no way of knowing, or finding out. And, no, I did not take any pictures. That could certainly explain the reddish tint perhaps left behind to mix with the proper gear oil. Unless someone knows of a gear oil that is specifically red (ish), I'll just have to let it go at that. It still seems to be handling all right.

So, another question. This 2.4 4 wheel drive, is in fact front wheel drive, yes? When I engage the button for 4 wheel drive, to my way of thinking, it should engage the rear driveshaft. But, a friend told me the rear shaft actually turns all the time. I thought that would be all wheel drive, not 4 wheel drive. The gear oil in the rear differential was quite dirty when I changed it...that would seem to acknowledge the idea of the rear drive shaft turning all the time. So is there an actuater ? sp. that kicks in the rear axle shafts, and are they limited slip? Geez, whatever happened to old fashioned Warn hubs that you had to actually get out of the vehicle, (usually when it was already knee deep in mud, sand or snow), and lock them in...this modern technology has me all confused. Thanks for all your answers.
 
#11 ·
My first thought was that you mistakenly drained the tranny fluid. I have seen this done numerous times when people are changing out their engine oil. Only then to overfill their engine oil and drive around with no fluid in the tranny.

Traditionally a transfer case is lubed with ATF. I can see someone mistakenly filling it with ATF instead of a gear oil.

Most 4wds these days no longer lock and unlock hubs, be it auto or manual. Thus the gears in the diff always spin even if they are not driven. The RAV is pretty unique in that is grabs a spinning powered shaft to engage the rear for 4wd. Most tend to engage the front shaft (which spins due to the front wheels rolling) in the transfer case somewhere.
 
#7 ·
Your RAV4 is in front wheel drive 98% of the time. It has an electromagnetic clutch just in front of the rear differential. This clutch kicks in automatically when needed. It is used briefly when taking off from a standing start. Of course you can lock it in with the LOCK button, but it will release when you exceed 25mph. This document will explain it all in detail:

https://www.rav4world.com/d1/attachments/pdf/2006/2006_4wdsystem.pdf
 
#8 ·
Thanks JuneBug. I read the pdf, quite impressive. These things have come a long way since I was a kid. I had no idea. Apparently, even my '93 GMC pickup is a dinosaur as far as technology. Let's not even consider how simplistic and outdated my old '66 Chevy is! (been driving it for 37 years!) I'll try to update my signature again, and perhaps post some pictures.
 
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