Red oil in the diff ?

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Mar 31, 2009
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I just acquired a 1978 Datsun 280Z. As per my usual, I have been very busy changing out all fluids for new. When I drained the rear diff, the oil was very dark in color, but with a very definite red tint to it. I have only ever used your normal brands of gear oil(Mobil , Valvoline, Shell, etc) and have never seen an oil for a diff that had a color like this. It was thick like a diff oil should be, so I doubt it was ATF. The fact that it is still running should prove that. I replaced it with the appropriate weight Valvoline synthetic gear oil, and it's quiet and smooth. Just curious as to what brand this may have been, as the previous owner was a little suspect in his maintenance routine. Just ask me about the possibly 31 yr old brake fluid I flushed outta this thing !
 
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Some of the specialty oil companies add red dye to their gear lube. I have seen red gear oil from TRC, Cenpeco, LE, & Horizon; there are probably others if you look around.
 

travlnman

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I had assumed as much, but wanted to be sure. Most of what I have seen so far on this car indicates the previous owner was not too sharp on PM's. When I flushed the brake system, what can only be described as black "blood clots" came shooting out of the lines. I just stick to the normal stuff, readily available, priced right, and has worked for hundreds of thousands of miles on all types of vehicles.I have personally logged nearly a million miles on what you can buy at your local parts store or wally world, with no issues. Whatever it was , it was overdue to be changed like everything else. Thanks for the input.
 
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I've never personally run into Red diff oil. However, the smell of diff oil/gear lube is a very specific smell. As long as I cringe at that smell when I recognize it I know what it is no matter what the color. If you're suspect about what wsas in there you might pop the axles out and check for outer axle bearing wear. If it's not the right fluid those will usually be the bearings to go first.
 

travlnman

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It definitely had that smell, like sulfer , which is normal I believe. I'm just not that into the boutique oils or stuff that is not over the counter. I don't suspect any unusual wear right now, as all is quiet and smooth. I plan on going through the entire car, from front to rear, and top to bottom before it's all done. If there are any problems, I'll catch them then.
 

MolaKule

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Hmm, we used to sell an extra HD racing gear oil with red dye in it. But I can tell you it had a very definite diffy lube smell to it.
 

travlnman

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All sound like good possibilities. Either way, it needed to be changed. "well done" would be a good word to describe it. I have really grown fond of the Valvoline synthetic stuff. Very smooth in my Z and my Ranger.
 
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Mystik JT-7 gear lube is also dyed red. I used both the 85W-140 and the 80W-90, and they are red for sure. If it wasn't for the fact that fluid coming out of the bottles had the distinct smell of sulfer and had the thickness of gear lube, I would have thought I was working with transmission fluid. It was that red. Maybe Mystik uses the same dye in their gear lube as in transmission fluid?
 
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travlnman

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That sounds exactly like it. I don't take this old boy for the type to search around for it though. Not sure how readily available it is OTC in Georgia, which is where the car come from.
 

MolaKule

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 Quote:
Maybe Mystik uses the same dye in their gear lube as in transmission fluid?
Yep, that same dye is soluble in just about any oil.
 
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