What Diff Oil to use

[batguano]

I have been running LE607 ever since I got the 4.56 final drive from Hardtopguy. He said it is the best for keeping the system cool.

While it may be cool, it sure is noisy. I had expected that it would settle in and get quieter as I put some miles on it but that hasn't happened.

What is everyone using and is there any substantial difference in noise or temp?

Mine is loudest between 50 and 60 MPH.

[fltsfshr]

Puddy's got a special recipe for 456's and 7's.

" If you have it available to you the LE-1605 90W gear oil is very good.

I use A blend of Lucas oils


In a stock diff use 70% Lucas 80/90w oil and 30% Lucas oil stabilizer. The stabilizer will help keep the oil at the 90w number and the anti shock additive will help keep the oil from braking down under pressure.
In a 4.57 you can go 60/40 on the blend, it will keep the rear a bit quiter "

I just order 1605 from stratocaster

[dlq04]

I like Redline 75w90.

[gomarlins3]

I have used LE607 and now use Mobil1 75W90. Nothing wrong with the LE607, but it's hard to find and ordering it on line isn't cost effective due to shipping.

[ninja]

I just bought some LE1605, will see how that compares... I've used LE607 in the past and also currently on Mobil1 75w90.

IMO the Mobil 1 causes the diff to howl more than the LE607 did.

[Justin6264]

I have been running LE607 ever since I got the 4.56 final drive from Hardtopguy. He said it is the best for keeping the system cool.

While it may be cool, it sure is noisy. I had expected that it would settle in and get quieter as I put some miles on it but that hasn't happened.

What is everyone using and is there any substantial difference in noise or temp?

Mine is loudest between 50 and 60 MPH.

If you find something that quiets it down, let me know! I run LE-607 and between 50 and 60MPH is the loudest for me too.

[batguano]

If you find something that quiets it down, let me know! I run LE-607 and between 50 and 60MPH is the loudest for me too.


I'm leaning towards Redline right now.

[hecash]

The guys in the race shop at King Motorsports were dumping praise on REDLINE HEAVY SHOCKPROOF (Red Line 58204) when I last spoke to them about my pumpkin gear oil.

REDLINE SAYS:
The Viscosity Characteristics Allow The Lubricant To Resist Throwoff And Provide A Film Thickness Similar To A 75w250 Grade, While Providing The Same Low Fluid Friction As An Sae 75w90.

[kgf3076]

Redline 75w-90

[desmo4]

Redline 75w-90

I second the motion

Jonathan

[Saki]

From everything I've read and tried, Mobil1 75w90 is the best or at least as good as anything else, including Lucas.
My drains are typically dark gold now when I change diff fluid, and I recommend it.

[repiv]

The guys in the race shop at King Motorsports were dumping praise on REDLINE HEAVY SHOCKPROOF (Red Line 58204) when I last spoke to them about my pumpkin gear oil.

REDLINE SAYS:
The Viscosity Characteristics Allow The Lubricant To Resist Throwoff And Provide A Film Thickness Similar To A 75w250 Grade, While Providing The Same Low Fluid Friction As An Sae 75w90.

Not sure if this is the same stuff but I was given a bottle of this to test some years ago.
Here is a scan of that oil analysis after only about 1500 miles:
http://forums.s2kca.com/photopost/data/15353/medium/Redline_SP_analysis.jpg

You may have to "save as" and use a magnifier to read the fine print, but look particularly at the top where it states that WEAR is "ABNORMAL". And below in the section "wear", it says, "Gear wear is indicated". And the last section, "The oil is no longer serviceable".
This gear oil was touted as a great gear oil and was targetted for our cars. I'm afraid it didn't do so good. I have steered people away from this fluid since. It may be OK for track use where you might change it after every other track day, but for daily use, I don't trust it.

Insofar as noise suppression for these Richmond gears, I think a thick fluid like the LE product "should" do as good a job as any. Perhaps it's time to try something a little different. By this, I'm talking about a GL-5 fluid in a wide range multigrade fluid like a 75W140 or 90W140 if this exists in your marketplace. The Richmond gears have always presented a challenge when it came to the suppression of gear whine. The whine is not necessarily indicative of alarming wear, but it can sure get on one's nerves. I think a caution should be stated that a fluid that suppresses gear whine may not always be good for gear wear and longevity. It may not be possible to cater to both issues.

[Justin6264]

That is a very interesting oil analysis, especially after only 1500 miles! You may be correct in that we are chasing two incompatible goals in trying to quiet the diff while maintaining for wear and longevity.

There are always the options of improving the stereo and replacing the exhaust to cover the whine of the gears....:D

[batguano]

Thanks Dave, That was very convensing (sp)

[dlq04]

I've heard the same bad reports on the Redline shockproof. Don't confuse that with Redline 75w90.

[hardtopguy]

The LE-607 has been reformulated and is now called LE-1605. For us in the differentials, it is the same fluid. They reformulated it to reduce the size of the molecules. This way the won't be filtered out in other applications.

[yinlun]

I've used shockproof heavy before on my Stealth. The 3Si guys all say you have to mix it. And I've always ran it with a 50/50 mix of Shockproof Heavy and 75w90 in the rear diff. Several track days and never had issues with flakes, and it was very quiet. Haven't used it in the S2k, maybe it's different? Or maybe it was meant to be mixed?

[S2k Dude]

Question, how do you know the replacement gears are properly shimmed and have the correct backlash? Maybe you're looking for a band aid fix (thicker gear oil) rather than looking for the real cause?

I ask because I've personally seen a few rear diffs not installed properly and had terrible gear whine. One in particular, when the differential was removed (at another shop) to look at what might be the problem, you could see an undesirable wear pattern where the ring & pinion were making contact. In this case the first installer did not shim the gears properly, they just replaced the OEM gears and used the same shims that were there. I'm sure the machining tolerances also play a part as well.

Once the proper shims were put in and the backlash set properly, the gear whine went from annoying to very tolerable.

[Randy W]

The 456's are LOUD.

I'll be swapping soon, but have been using Swepco.

[alvanderp]

I've heard the same bad reports on the Redline shockproof. Don't confuse that with Redline 75w90.

Correct - the Heavy Shockproof and the 75W-90 Synthetic(which I personally use) are different products. I have had nothing but good things to say about RedLine lubricants, when used in the appropriate application. I have been using them for years on more than just my S2k, with great results. That said, any of the other oils mentioned above should work fine as well.