Some people have reported that Redline MT90 in the manual transmission can be notchy in the cold until warmed up (although currently I have it and it's crisp when cold). Others have reported that Royal Purple Max Gear 75W90 can sometimes lead to grinding (because it's a GL5) and may possibly cause premature wear.

I currently have RP Max Gear in my differential and I'm going to change it with more of the same, which means I'm going to need two 1-quart bottles. Because the differential will take about 1.5 quarts, I will have 1/2 quart left.

With the 1/2 quart of RP Max Gear that's left, what if I put it into the transmission and then fill up the remaining with Redline? Are the two products mixible? My thinking is to reduce the chances of premature wear/grinding (from RP Max Gear) as well as the chances of notchiness (from the Redline).

I have read quite a few threads where people do the 1/3 Redline MTL to MT90 mix. However, I have not found a single thread or post reporting that someone mixed the two brands like I'm suggesting.

What do you guys think about my idea?

 

Considering the tranny takes 1.8 quarts, you'll still need 1.3 quarts of Redline and so will buy 2 quarts regardless. It's probably better to stick with pure MT90 if it works for you. My transmission doesn't like MT90 and prefers Royal Purple, but I have a feeling that might be down to a tolerance issue.

I don't think Royal Purple is harmful to synchros. While the MaxGear is a combo GL-4/5, it seems that it's been formulated to not eat synchros like a pure GL-5.

 

I had RP MaxGear and just switched to Redline MT-90, and the Redline MT-90 is less notchy and grind less when cold.

I drove a winter when cold (temps below freezing) with my stock fluid, and I had cold gear grind when doing 1-2 and 2-3 for the first couple of minutes (first 5-6 shifts or so). If I paused slightly in neutral between shifts, there'd be no grind.

When I switched to RP MaxGear next winter, I noticed that the movement of the shifter was a lot easier (the fluid didn't feel as thick when it was cold), and I felt less resistance and had smoother engagement. Yet I still had the cold grind similar to stock, maybe a bit better (it went away sooner).

When I switched to Redline MT-90 this winter, I noticed that the stick movement is just as smooth as RP, if not smoother, and the fluid also feels "thin" really quick (almost right away), but the cold grind is significantly less. It's still there (not eliminated), but it goes away in 30 seconds or so, in the span of 2-3 shifts. Personally, I wish I went with Redline MT-90 right away. I also noticed that shifting is even smoother when warmed up.

So I recommend you go 100% MT-90. But that's just my personal experience.

 

I had the M/T 90 in and tried the R/P MaxGear.... M/T 90 wins out easily. The RP is very stiff and notchy in the cold and takes longer to smooth out.. I will be changing back in the spring.

 

You use Mobil 1 synthetic gear oil for the tranny?

 

I wanna try Redline for quite a while, but I still got 4 bottles of RP in my garage waiting for me ...

After rP i will try redline, then I will go try other stuff like CRH. Im sure they all gonna work fine.

 

it was 17 degrees last nite

Im ok. It grinds a bit if I shift too fast tho. but after maybe 1 minute, it shifts just fine.

 

What Mobil 1 oil do you use in the transmission CRH?

 

I think they only have 1 kind ... Synthetic Gear lube. 2 weights

http://www.mobiloil.com/USA-English/...ubricants.aspx

 

isn't that a GL-5 gear lube for diffs?

 

Thanks for all the replies.

I remember a couple of guys in some old threads reported that their Redline actually shifted better in the cold or immediately after starting the car before it warmed up. I also feel my Redline in the gear box shifts really well when the car is cold. Obviously, this is the reverse of most people's reporting Redline being notchy when cold and that Royal Purple isn't. Now some of you guys here are saying that the Redline is less notchy in the cold than Royal Purple.

I wonder if it's really a difference in tolerance issue across different people's transmissions or if it's differences in precise mixing due to quality control issues at Royal Purple and Redline.

 

I want to ask again is there any reason you can think of against mixing the Redline and Royal Purple in the trans? Is it like engine oil, where it's ok to add different kinds of engine oil together?

If there is no reason that they can not work together, then I think I'm going to try the experiment.

 

Interesting, it is GL-4 or 5. I had always assumed it would be GL-4 only, but I guess not. I also find it interesting that it calls for 75W90; didn't Mazda at one point spec a straight 90 only to change it since nobody could find a 90?

By the way, what's with the transmission oil capacity? In the manual for checking the level it says to see if the level is near the brim. However, even putting 2 quarts into the transmission doesn't fill it to the brim.

 

Since we're on the subject of transmission oil, does anyone have any experience with NEO gear oils?

 

This was my experience as well, so I just went to 2 quarts and stopped there. Could it depend on if your car is perfectly level? People have mentioned this in threads 3 years ago. If the rear is a little higher than the front, I can see how the capacity might go up a little.

 

Makes sense, Charles, that's what I thought also.

 

I hate you guys !!! you guys have friends working at this and that and can get unlimited amount of free oil !!!!

 

Livonia, MI ???

beers

 

roush.

but mobile one means penske... just dont know where they are based in detroit..

btw, pm...

beers

 

Ha ha I put Mobile 1 in my tranny before I even knew anyone else used it.

I second the motion.

Many track days. She works fine for me!

 

I get Redline for $4 a quart, which is why I decided to give it a second chance. At that price I'll probably still keep it in the diff, but my tranny needs something different.

 

I use the BG Syncroshift 2. I performs far better than the redline, amsoil, RP, or stock fluids I tried.

 

shameless plug!!!!!!!

beers

 

Oh ****, so now I have to look into BG Syncroshift 2, whatever that is. Why couldn't he (Kenny) just stay out of this thread?

 

Just searched BG outside this forum. First, all the reports about Syncroshift are from 4 to 7 years ago on forums such as the Evo forum. Users had mixed results and some people could not find a difference between it and Redline. Furthermore, Royal Purple was never mentioned (my guess is because Royal Purple wasn't available back then). Can't find current user reports, not even on this forum. Very Strange.

Second, the BG website has a bunch of stuff for automatic transmissions, oils and flushing machines. But nothing for manual transmissions and no Synchroshift. Even stranger.

Sounds like another ghost product. I'm staying with Redline and Royal Purple.

Thanks for wasting my time.