I'm going to give the Neo HD 75w90 a shot when I change my diff/trans fluids before the upcoming trip to DGRR

 

I've tried just about everything out there in my 11 years and #1 imo is Amsoil GL-4 rated 75w-90 gear lube.

 

I switched from Royal Purple to RedLine. The RP was in there a while and was always great. As soon as I put the RL in there my shifting got really notchy. Really hated it so there is an example of going from old fluid to new and not getting good results. I then swicthed pretty quickly to Neo. It is much better than RL in my opinion but still not as good as RP was at any point during its service life.

 

Viscosity shear on Redline and RP after 15k miles is pretty bad, based on threads I've seen on BITOG. I'd pick Mobil 1 before either of them, and Amsoil before all. http://www.amsoil.com/storefront/mtg.aspx

Instead of voicing random opinions, we should start a UOA trans and/or diff oil thread and get some hard humbers. What good is "feels better"?

 

This time around I tried Amsoil and for some reason the first time I was hard on the transmission on a canyon run it became VERY notchy too the point that I was locked out of 1st gear...I had to wait for the trans to cool down to drive again! After that one day it has never done that again even after beating up on it at the track for a whole day, no complaints.

Can anyone explain why the first hard run was notchy??

I think I'm gonna try Mobil 1 next round and see how I like it....

 

The original owner of my car put in redline. When the car is cold I don't think it feels smooth at all. So far I'm not impressed with the redline. It is a bit old since it was put in back in the mid 90s but the mileage is low. Looking forward to trying some neo or amsoil. I can get amsoil really so I might go that route.

 

Was it MTL? If so, that's too light for the FD. From Redline, make sure to use MT-90.

 

So I decided to change the fluids in my FD that I've owned a little over a year now, did some research and decided to go with the NEO synthetic 75w90HD for gearbox and rear since there is a lot of positive feedbacks here. I ordered a gallon of the NEO and when i got it,I noticed that the oil seems pretty thin (watery). What do you guys think?

 

If you race, amsoil shockproof and never look back. For the street, redline is not too shabby. Neo is good but doesn't come close to amsoil. I've used redline, neo, mobil 1, and even motul.

 

From what I was reading you all spoke highly of neo synthetic and by reading the thread I'm going with Neo my self . I currently have Royal Purple in my carbonetic LSD

 

What's up, so my FD has been on jack stands over the winter and I finally decided to change the gear oil before I took it off. After reading threads on here I decided to go with the NEO 75W 90HD gear oil which I put in there this past weekend. I had 2 buckets, drained the old oil which came out clean no metal shavings nothing and I filled the next bucket with the NEO gear oil to make sure I put in the same amount that came out. It took the entire gallon of NEO gear oil. So basically 1 gallon came out and one gallon went in and I didn't over full cuz I kept fulling until it started coming back out the full hole. Now before I change the oil the gears shift pretty good ,all gears was smooth except that notchy 2nd gear. Now with the NEO gear oil in there its a bit stiff to go into all gears but there's no grinds or notchy feeling just little stiff and I don't feel like I'm putting it in a gear, its just slides rite in. Did anyone experience this or is that just how the oil is? I don't know but I don't like it so any help is gladly appreciated. Thanks.

Shiva.

 

If I remember correctly the manual transmission holds 2.6 US quarts. 1 gallon sounds like a lot to me.

 

That's the same thing I was thinking but its the same amount of the old oil that came out cuz I measured the amount of oil that came out with the amount that i put in. I had 2 same exact buckets and I made sure the level of both oil were the same and also I know a lot of people who fulls the box until it starts coming back out the full hole and that's it. I'll be taking the car to my mechanic this weekend to do some other stuff so ill have him check it out. Thanks.

Shiva.

 

I've been running NEO for the last year and a half, before that it was Red Line MTL and I notice no difference in any shifting characteristics - still have the little notchiness into 2nd (in cold and warm weather), and as for the stiffness in the action you mentioned, not for me.
I was under the impression NEO is a Cali product, just like Red Line.

 

Thanks! Another forum member said its basically to much oil in there and that I only need 2.5 qts which I knew but I took out one gallon and as I was fulling I just waited for it to start coming back out and it took a gallon. I'll get a measuring jug and put the rite amount in there and see what happens. Thanks.


Shiva.

 

Easiest accurate way to do it is with a fluid pump. You can screw it onto a quart container and pump two full quarts and then .6 more.

 

I've had Neo since 2005. Same engine, same tranny, same diff, no issues...

 

^ Me too. Good stuff.

 

FWIW,

Mitch Piper at Piper Motorsports, who was Peter Farrel's chief mechanic in the IMSA days, did my transmission instal, and put Motul racing fluid in it.

 

Just from my experience I preferred how the Amsoil worked in my old FD. Even when cold it seemed to keep the synchros happier. As soon as KD rotary installed my 6 puck clutch and refilled with Redline it got notchy and liked to grind when cold.

Have used royal purple also and would choose Amsoil over all of them. It made a noticeable difference to me, even over whatever Mazda was using back in the day.

 

I know that this is an old thread, but I just switched from Red Line to Neo in my tranny. The Red line was several years old, and I never had any issues with it. I had heard good recommendations about Neo from members here, and from Mariah Motorsports. Anyway, I can feel an improvement. The tranny definitely shifts smoother and easier than it did with the Red Line. I put Neo in the rear differential also. I give it Neo big thumbs up

 

Quick question! I just buy some royal purple gear oil and the only oil i found is call Maxgear!!! It is the new name for the HD oil that we talk here??

 

So I had a major transmission rebuilder tell me the oil used from the factory (not sure which it is) is the best to use. The synthetics like neo don't allow the transmission to operate as designed and can actually damage the transmission.

Now if a transmission shifts smoother I'm not sure how it would damage the transmission. Any insight into what I was told?

 

He is correct. The Mazda engineers made damn sure that the fluid, additives, and materials in the transmission did not have any compatibility issues.

Main thing to worry about is if the oil is yellow metal safe. As in corrosive or not to syncros and bearings. GL-4 is a safe bet. Some GL-5's are OK too. The best is if the container actually states yellow metal safe. I now personally use CRC Sta-Lube 80w-90 GL-4 Gear Oil from NAPA. It says yellow metal safe right on it. I would have gotten Mazda spec'd gear oil if it was more convenient.

Some additional reading: Yellow metal safe gear oil | ATF, Differential, Trans, Brakes, P/S | Bob Is The Oil Guy

 

Hello Any opinions on which fluid is best for track use ? I was told to use redline , BUT after all the reviews here I'm kind of on the back foot .

I used royal purple with decent results . But it would ocasionally grind at the track when going into third . this may just be a synchro issue .

i'll be getting a new trans now and was curious what people seemed to like best when the car is getting abused on the track .. I can live with the fluid being notchy in the cold I can double clutch just fine

My priority is when its getting shifted time after time at 8k rpms . what works best then ?