Mobil One Synthetic fluids vs. Redline Synthetic fluids

[abc]

For your rear end differential and your automatic transmission which fluid would you choose to use and why?
The 75W/90 that comes in the Corvette is already a synthetic fluid but I'm not sure of which brand.
The DEXRON III (H) which is not synthetic comes in the A-4. I believe The new DEXRON IV can also be used in the A-4 but I don't know if it is synthetic.
So would you switch to a synthetic fluid on the A-4? If so which brand? Same goes for the rear end 75W/90 which brand?

[hddeuce]

I'm not sure this will help but I use RedLine Shockproof Heavy in my harley 5 speed transmission and it is FAN-TAS-TIC compared with the other synthetice I have tried - so I would chose Redline, at least for the differential.

[red01]

Why not use what the Corvette engineers recommend?

[abc]

Originally Posted by hddeuce

I'm not sure this will help but I use RedLine Shockproof Heavy in my harley 5 speed transmission and it is FAN-TAS-TIC compared with the other synthetice I have tried - so I would chose Redline, at least for the differential.

I am using Redline on my other car in the 5 spd. manual and the rear end differential. Can't tell any difference with rear end but with 5 spd. it made a day and night difference shifting is like a piece of cake real smooth made a difference between selling the car and keeping it.
I may use the Amsoil 75W/90 Severe Gear Oil on the rear end differential of C-6 Corvette. I keep hearing that Amsoil is the BEST.

[abc]

Originally Posted by red01

Why not use what the Corvette engineers recommend?

Because what they recommend is not synthetic for the A-4 transmission.
For the automatic transmission on the 2005 Corvette that would be now DEXRON IV and I don't think it is synthetic.
Redline makes a D4ATF that is suppose to work.
Amsoil has not come out with a comparable ATF yet for this application.
The rear differential uses a GM synthetic 75w/90 gear oil in it. I don't know which company makes the rear end fluid for GM, but I would think AMSOIL would be the best.

[c4c5specialist]

Hi there,
Dexron 6 is a partial synthetic, NOT A FULL synthetic.
The fact is that in the A4, you will NOT see a real change in performance over a standard Dexron 6 or the synthetic.
And, in order to keep contamination, you will need to change the fluid.
As far as the rest, there is NO confirmed data to indicate that any synthetic fluid in the A4 helps the longevity or shifting smoothness.
Rear end lubricant, GM or Mobil, both meets the exact same specification.
Allthebest, c4c5

[abc]

Originally Posted by c4c5specialist

Hi there,
Dexron 6 is a partial synthetic, NOT A FULL synthetic.
The fact is that in the A4, you will NOT see a real change in performance over a standard Dexron 6 or the synthetic.
And, in order to keep contamination, you will need to change the fluid.
As far as the rest, there is NO confirmed data to indicate that any synthetic fluid in the A4 helps the longevity or shifting smoothness.
Rear end lubricant, GM or Mobil, both meets the exact same specification.
Allthebest, c4c5

Keep in mind I don't track this car it is street driven and has 11,200 miles.
I Never heard of Dexron 6 Do you mean Dexron IV is a partial synthetic?
Now is it true and I know you are qualified to answer this, Should both automatic transmission and the rear end differential fluids be changed once car is broken in to remove those metal shavings?
It would be like the 1,000 mile oil change to rid the metal shavings in engine.
Would you change both fluids in rear end and auto transmission?

Now I understand that the DEXRON IV is what dealership will put in auto trans now as the DEXRON IV replaced the DEXRON III (H) and is suppose to be a better fluid and longer lasting fluid 160,000 miles.
Is the Redline ATF D4 synthetic fluid a better fluid than the DEXRON IV? Which one would you use and why?

In my 2005 manual it says to do an auto transmission service only if there are no leaks.
Then it goes on to say change ATF fluid and filter at 50,000 miles for severe service or at 100,000 for regular service.
Dealership tells me to do auto transmission service flush at 25,000.
Which one is correct?

For rear differential the 2005 manual states that there is no need to change this 75w/90 synthetic fluid unless there is a leak.
I was also told by a GM rep that the rear end differential fluid that comes in Corvette is life long fluid?
Who is correct here as i have never heard of this before.

Also is Amsoil synthetic 75W/90 Severe Gear Fluid for rear end superior to whatever 75W/90 synthetic fluid GM uses?
What does GM use Mobil One for rear end too?

Lots of questions but I appreciate your knowledge and information on this as I am getting different information on the preventative maintenance of these 2 components.

[Norseman]

IMHO it would just make sense to use what GM recommends. That way you preserve your warranty. I think they know what is best for their cars.

[abc]

Originally Posted by Norseman

IMHO it would just make sense to use what GM recommends. That way you preserve your warranty. I think they know what is best for their cars.

What does GM use for the 75w/90 synthetic gear oil for rear end? Mobil One?
Auto trans is DEXRON IV which is semi-synthetic?

[abc]

Originally Posted by Norseman

IMHO it would just make sense to use what GM recommends. That way you preserve your warranty. I think they know what is best for their cars.

In the 2005 owners manual it recommends that you don't change fluids on rear end or auto trans unless there is a leak.
Then it goes on to state change auto trans and filter at 50,000 for severe service or 100,000 miles.
Rear end differential is suppose to be life long.
I find all of this hard to believe.
Especially since the transmission and differential are located near the exhaust system. They are all packed in together so there is alot of heat down there with little space for cooling so I would think getting the best fluids would be the best or changing them alot more often but only if NECESSARY as it becomes too much work

[Norseman]

If you can afford it let them change it a often as you think is necessary to give yourself piece of mind. I run Mobile-1 in all my cars and motorcycles and use OEM's fluids for the diff on my cars and shaft drive on my bike.

[abc]

Originally Posted by Norseman

If you can afford it let them change it a often as you think is necessary to give yourself piece of mind. I run Mobile-1 in all my cars and motorcycles and use OEM's fluids for the diff on my cars and shaft drive on my bike.

So in your eyes Mobil One is as good as any other synthetic oil like Amsoil, Redline, Castrol Synthec, and Royal Purple?
It's not the brand of oil but the frequency of how often you change it whether transmission or rear end differential?

[Norseman]

I love Mobil-1. It's the best, it's a slam dunk.

[abc]

Originally Posted by Norseman

I love Mobil-1. It's the best, it's a slam dunk.

It is easier to find and the lowest price of the other synthetics like Amsoil or Redline.

[abc]

Originally Posted by Norseman

If you can afford it let them change it a often as you think is necessary to give yourself piece of mind. I run Mobile-1 in all my cars and motorcycles and use OEM's fluids for the diff on my cars and shaft drive on my bike.

Then how often do you change the fluid in the rear end? Also same question for transmission?
You can be a little different than others and use Amsoil.