Rear Differential Drain
Burning Brakes
Joined: Jan 2007
Posts: 853
Likes: 0
From: Slinger WI
Did you have an oil analysis done? There is the oil and the gm additive. I bet the additive wore out.
Regardless, changing oil just because you feel it is bad is wasteful. Have a sample tested, for 25 bucks. They will tell you the condition of the oil and contaminants within the oil.
But if people just want to change oil to change oil, its your money. If you dont know if something is worn with the oil, or within the parts, you are just wasting money in the long run. Its my opinion, nothing more.
I would be more concerned of 17 year old antifreeze and brake fluid, than my differential fluid.
Regardless, changing oil just because you feel it is bad is wasteful. Have a sample tested, for 25 bucks. They will tell you the condition of the oil and contaminants within the oil.
But if people just want to change oil to change oil, its your money. If you dont know if something is worn with the oil, or within the parts, you are just wasting money in the long run. Its my opinion, nothing more.
I would be more concerned of 17 year old antifreeze and brake fluid, than my differential fluid.
Le Mans Master
Joined: Oct 2008
Posts: 9,758
Likes: 49
From: Houston Texas
What people don't understand is letting your sit around is bad for it. Seals harden ,condensation and corrosion set it and fluids like to be cycled.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
I have always wondered where this "condensation" comes from, given that the differential is sealed.
My FSM says on page 0B-3: "The manual transmission or transaxle fluid does not require changing".
I also don't understand why this is so complicated. If you think the oil should be changed then do it. If not, then don't.
My FSM says on page 0B-3: "The manual transmission or transaxle fluid does not require changing".
I also don't understand why this is so complicated. If you think the oil should be changed then do it. If not, then don't.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
I don't know that sitting for years qualifies as "normal use". Also, car is engineered to last 100,000 miles...and many (most) are over that. So what to do??? The recommendation of THIS mechanic is to spend a few dollars and change the oil. Take a sample if you absolutely feel the need to know for sure.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
The reason I asked about condensation is that the volume of air in a differential is pretty small. I can't imagine there's much moisture in there.
I guess we should be shooting some nitrogen in there when we change the oil, huh? Back in the old days when I was doing darkroom work I heard about an aerosol can that had nitrogen in it that you could spray into your chemical bottles to displace the oxygen and prevent oxidation. I assume that stuff is still available. I don't remember the brand.
I guess dry air from a compressor would work.
I guess we should be shooting some nitrogen in there when we change the oil, huh? Back in the old days when I was doing darkroom work I heard about an aerosol can that had nitrogen in it that you could spray into your chemical bottles to displace the oxygen and prevent oxidation. I assume that stuff is still available. I don't remember the brand.
I guess dry air from a compressor would work.
Safety Car
Joined: Jun 2006
Posts: 3,629
Likes: 28
From: FL
The reason I asked about condensation is that the volume of air in a differential is pretty small. I can't imagine there's much moisture in there.
I guess we should be shooting some nitrogen in there when we change the oil, huh? Back in the old days when I was doing darkroom work I heard about an aerosol can that had nitrogen in it that you could spray into your chemical bottles to displace the oxygen and prevent oxidation. I assume that stuff is still available. I don't remember the brand.
I guess dry air from a compressor would work.
I guess we should be shooting some nitrogen in there when we change the oil, huh? Back in the old days when I was doing darkroom work I heard about an aerosol can that had nitrogen in it that you could spray into your chemical bottles to displace the oxygen and prevent oxidation. I assume that stuff is still available. I don't remember the brand.
I guess dry air from a compressor would work.
Race Director
Joined: Jan 2012
Posts: 17,062
Likes: 166
From: United States
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Race Director
Joined: Nov 2003
Posts: 12,222
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
The vent proves I was totally wrong about the condensation. Sorry for the distraction.
My car has 111K on it and the differential oil has not been changed since 1986 when I had a leak repaired. I'm planning on putting in a drain plug in the near future.
My car has 111K on it and the differential oil has not been changed since 1986 when I had a leak repaired. I'm planning on putting in a drain plug in the near future.
Race Director
Joined: Apr 2003
Posts: 17,701
Likes: 1,667
From: moraga ca
Race Director
Joined: Nov 2003
Posts: 12,222
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
Again, not the expert, just a guess. If wrong, I'd be interested to know the real reason.
Race Director
Joined: May 2001
Posts: 14,165
Likes: 9
This is absolutely beyond absurdity at this point. What are you trying to prove Kracken? Nobody said that having the oil analyzed was a bad idea, but here's the deal. If you have to crawl under the car, draw out a sample, then pay $25+ to send it off and have it analyzed, wait weeks for the results, only to determine what?
1. Yeah, it's fine, but now it's low on fluid because of what you sucked out so you're gonna have to buy new fluid anyway to top it off.
OR
2. It needs to be changed, which will cost little more than the analysis did in the first place.
It's a great THEORY if you're running a fleet of vehicles that you're putting a ton of miles on and you need to save every penny. But, he doesn't have fleet of Corvettes, he has ONE. Why spend $25+ dollars HOPING that your oil will be good enough to continue to use when you could just spend $35 and change it and then you KNOW.
You seriously don't want to get into a "credentials" pissing match around here, I promise you you'll lose. When you've driven your car as many miles going forward as most of us have in reverse then we'll be happy to listen to your input.
But then again, I'm an IT guy, I CAN'T know ANYTHING about cars. I guess that CDL driver's license just jumped in my wallet too.
Racer
Joined: Jan 2007
Posts: 380
Likes: 1
From: Toronto Ontario
Nathan, you could not have said it better. I find the C4 section to be the most informative of the entire Forum and it's because of a bunch of guys who don't mind sharing their knowledge and expertise with guys like me that are not as skilled or knowledgeable. It's not difficult to sort out the guys who've been there, done that and have the expertise, certified or not versus the relatively smaller group that feels the need to provide an opposing opinion just because they want some air time or need to get their post count up. I'm by and large a lurker that enjoys this forum and don't usually make comment. It' because of the knowledgeable guys here that I tackle small jobs on my C4 that I otherwise would be intimidated by. To you real experts who have walked that mile and have the expertise please don't desert us.
Instructor
Joined: Feb 2007
Posts: 132
Likes: 3
From: CRYSTAL RIVER FL.
Hawk:
I have the "kit" the Ackman shows on his link. I bought it before my lift was install. While rebuilding the rear end (bushings) I just drilled and tapped it on the bench. But I did 1/2" NPT. It's just sitting around collecting dust. Never used. Sooooooo............. you can have it for just the shipping. Just send it on free to the next guy. Share the wealth. Let me know.
Dave
I have the "kit" the Ackman shows on his link. I bought it before my lift was install. While rebuilding the rear end (bushings) I just drilled and tapped it on the bench. But I did 1/2" NPT. It's just sitting around collecting dust. Never used. Sooooooo............. you can have it for just the shipping. Just send it on free to the next guy. Share the wealth. Let me know.
Dave