I'm going to change out my diff fluid and I was wondering what everyone recommends? The only one I've heard about was Mobil 1 75W-90 GL5.

What comes in the car from the factory? Does honda make a diff fluid?

 

I put 75W90 Red Line Diff fluid in mine... its about $10
its red line... good enough for me
btw, the stock fluid that came out wasnt completely sludge... but it was still nasty.
I haven't noticed any difference since changing the diff fluid..4000 ago..but as I said... its Red Line
hth

 

I would use stock Honda fluids so there are no warranty issues if the differential blows up.

 

My dealer says Honda does not package differential fluid to go. They only have it in bulk. When I changed mine, the old fluid was gray like it had moly in it. The new (castoroil 85/90) was clear.

 

i use redline lightweight shockproof. I LOOOOOOOVE the feeling of clean diff fluid! i change mine every 5-10k since my last diff blew up.

 

I have been using Red Line MT-90 in my transmission for the last 700 miles. It has never shifted better than it does now, I'm almost to the 7,000 mile mark. My S2000 is a early 2001 and I have experienced some 1st > 2nd problems. Red Line states their Synthetic MTLs contain NO reactive sulfur which will chemically wear synchros and cause a pre-mature failure. Red Line also claims to have the correct "coefficient of friction", it's not to slippery like motor oils. The "correct coefficient of friction" is perfect for rapid synchro engagement and allows for high-speed upshifting or down shifting. I have hit some of the sweetest speed shifts ever using MT-90 !!! Red Line makes 2 synthetic tranny fluids which could be used in our cars.

MTL = SAE 70W80 API GL4 gear oil with viscosities =10W30 motor oil.

MT90 = SAE 75W90 API GL4 gear oil with viscosities =10W40 motor oil. This is the one to use in the S2000's transmission.

I'm also using Red Lines 75W90 GL5+ Hypoid gear oil in the differential. This oil does contain sulfur(you can smell it), an additive for limited-slip differentials. It should not be used in manual transmisions due to its exterme slipperiness. Dino 90W Hypoid gear oil may take upto 5 minutes to warm up and start to lubricate. Most synthetics flow freely at 50 degrees below zero. Guess which one protects better? And you've been driving for 5 minutes.

Synthetics do preform better then dino, they can improve drivetrain efficiency by 5% , that's a reduction in friction which intern reduce running tempertures upto 70 degrees.

The bottom line here is that you are getting more power to the rear tires. This is one of the cheapest mods you can make that really does make a difference.

 

[QUOTE]Originally posted by StwoK
[B]MTL = SAE 70W80 API GL4 gear oil with viscosities =10W30 motor oil.

 

naishou ....... Yes, both the owners manual and shop manual state that if Honda MTF is not available 10w-30 or 10w-40 motor oil could be used for short time. By using the MT90(Manual transmission oil) I gain a little extra protection, it is still within Honda's recomended specs!

In your differential, you said that you're using 75w-140 GL5/GL6 lube. Honda calls for a 90w oil GL5 or GL6. You're probably losing some performance by using a thicker oil. Who knows, you may never get the differential hot enough for the oil to thicken to 140w.

 

 

I had my differential fluid changed at 5000 miles to Redline MTL and had a bottle of Redline LSD break in fluid added. For those questioning the MTL in the diff, I asked the service advisor and the tech, who is also a S2K owner, three times about the MTL and they both gave me the OK. The doesn't seem to drive any differently, but it has lost the "moan" experienced during sharp low speed turns, like in a parking lot.