Transmission Oil Life: Royal Purple versus Redline
 

Hey folks,
I'm due for my 30k service, so I figured it'd be a good time to put in some better oil into the transmission. I was going to put Redline in, but then a friend with an M3 heard of some folks with other M3s having some issues with Redline. Things would feel great at first, but then after a few thousand miles, the shift quality would regress.

Anyone here have a similar experience? For those that have put in RP or RL, could tell us how many miles you have and if you still think the shift quality is improved?

Thanks!

~ Matt

I've been using Redline for the last 10K miles (34K on the car) and can't say I've noticed any difference. I was thinking of trying RP because my 8, when cold, will grind if I don't shift REALLY soft. Once the car warms it shifts smooth though.

So, what you are saying is that before putting the Redline oil in, and after putting the Redline oil in, it felt the same and has continued to feel the same? (this is what I think you are saying)

Or that for the entire 10K that you've had the Redline, it hasn't changed, however, there was a difference from before putting the Redline in, to after.


Thanks for your input!

~ Matt

just hit 30k on rp in the tran and diff... time to change it...

the stuff makes a huge difference in the trans... for the better..

as to rl vs rp... a cant believe there is much difference..

beers :beer:

Cool, so you've put on 30k miles with Royal Purple in your transmission and it has been consistant for the entire time? That's good to know. Thanks!

~ Matt

yep.

beers :beer:

I have used them both for various cars, no big difference.

Just switched to Redline this weekend. It seems that when cold, my car doesn't like going into 1st when moving, but once the tranny is warmed up the shift quality is fantastic. I use straight MT-90, so maybe going with a MT-90/MTL mix is better for shifting when cold.

I have been using redline MT-90 for the last 25k miles and i have noticed the same. In the morning, when the tranny fluid is cold, it's hard to shift into gear. I did not notice the hard shift with the OEM tranny fluid.

swoope, does the same thing happen for RP when the fluids arent warmed up, and are you using the RP Syncromax in your tranny?

I have used amsoil in many different cars and am really happy with it, I've got it ready to go in when I get around to doing it. I researched redline, RP and amsoil before deciding on amsoil. Redline it seemed many people had hard shifting when it was cold. I haven't heard any complaints about RP. Since my past experience with amsoil is steller i decided to go with them. I used it in the engine as well (please lets not start a synthetic engine oil thread).

What about oil weights? In the 2004 manual for the LSD they recommended 75w90 and the same for the trans both gl-5 spec. I went to the mazda dealer and was asking about the mazda oils (which they use for every mazda nothing special about it) and they put 80w90 in the lsd and 75w90 in the trans still both gl-5 spec. What weights do people use in the trans and diff?

yeah... same problem here w/ my redline. shifting when cold always grinds. getting into 3rd gear is really nasty in the morning for me & keep in mind i live in florida. i must say though that when it warms up it feels great!

I have had RedLine in for 25K and will put it in again. Made a big differance vs OEM. You do have to shift ez the first few miles when it is cold but it is worth the cost. Have not used RP but everyone seems to think they are about the same.

I've been using Red Line in gearbox and diff for about 10,000 miles. I did notice an improvement over the stock fluids, although it wasn't earth-shattering. The Red Line seems to provide a little more "cushion", is about as well as I can describe it. You need to slow down the shift just a tad, and then it rewards you with a nice smoothness. It does seem to get a little gooey when cold though it rarely goes below freezing here so it's not a big problem. If I were in a cold climate I'd probably go with the MTL or a mix.

I'm always surprised by the number of people who have trouble getting into 3rd. On my box, the 2-3 shift is absolutely the smoothest and fastest on the box, and 4-3 is good. Going into 4th usually gives a bit of a whine for me though. Crazy how even mass-produced things with thousandth-inch tolerances can still end up so different.

It feels the same and continues to feel the same from the stock fluids, but needs to be rev matched when shifting to keep it from grinding when cold. The only BIG differnece is the 2 -3 shift where it shifts much smoother.

Cool, thanks for the clarification.

they are both quality oils, trying to make a determination on which is better for every day street use is pointless exercise in anality

fwiw, I ran Redline in numerous BMWs (street & competition) without issue, if there is an issue it was most likely from using the wrong grade/type oil for the application

While I would think there wouldn't be much of a difference, there's already been one (cold transmission shift difficulties with Redline) that's come out. More than anything, though, I was hoping to find out after 10k, 20k, or more miles, how the two compare in terms of shift quality.

~ Matt

I was also comparing (1) RP Max Gear, (2) Redline MT90 and (3) Amsoil. Here is the specs I gathered.

viscosity@100C cSt: (1) 21 (2) 15.6 (3) 14.7
viscosity@40C cSt: (1) 144.5 (2) 90 (3) 84.5
Viscosity Index: (1) ? (2) 185 (3) 177
Brookfield Viscosity@-40C: (1) ? (2) 320 (3) 43.6
Flashpoint (F) (1) 430 (2) 465 (3) 410
Pour Point (F) (1) -40 (2) - 49 (3) -47

I don't know the differences among the "types" of viscosity. Can anyone explain the differences? There seems to be quite a bit of differences even though all of them are rated as 75W-90. Since it can become chilly around here in Alaska (occasional -40 to -50F), Amsoil (or redline) seems to be the best for me (pour point of RP is a little higher than amsoil or redline). For the rear differential fluid, Amsoil has the lowest pour point (-60F).

Anyone have any real evidence to show that the LSD additives in the Royal Purple are harmful to syncros? I have heard this argument, but no case studies or anything.

This would be one thing that could sway me more towards the Redline.

30 k miles no problems.. but i think the problems you mention are with the lsd, not the syncros.

beers :beer:

No, from what I've heard the LSD additives can be harmful to the integrity of the syncros, b/c the additives can cause the metals in the syncros to become degraded. (i.e. the soft metals of the syncros are not intended to be used with LSD additives, which seems to be gl5 stuff, wereas the gl4 stuff doesn't contain these additives). I would imagine this would be over a rather long period of time if it is true.

sure,

ok. fine..

beers :beer:

I put Redline in both my tranny (MT-90) and differential (75W90) at about 1k miles. I just changed them both a couple weekends ago (at 18k miles). Funny thing was that other than some gunk stuck to the drain plug magnet on the tranny, that fluid looked just like brand new oil coming out of a fresh container. The differential, OTOH, was very dark -- not black like used motor oil, just way darker than the tranny fluid (and yes, there was a lot of gunk stuck to its drain plug magnet as well). What does this mean? Hell if I know. I might try some Royal Purple next time around, but for now, the Redline has worked very well for me. As for hard shifts when cold, that went away completely when I put the Richard Paul shifter in. It's almost like that thing has a microchip in it that guesses what gear you want, as shifting is so effortless and easy you just almost don't even have to think about it. I really hate to sound like a Richard Paul commercial here, it's just that I get sooooooo very pissed off when I buy things that don't work, when I buy something that does work (and greatly exceeds my expectations), I have a hard time refraining from singing about it from the rooftop. :boring:

I just purchased two quarts of royal purple max gear 75w90 which is a GL4 & GL5 compatible gear oil. I talked to a royal purple tech over the phone and he recommends the max gear for the rx-8. He told me that the max gear oil does not contain the harmful additives that other GL5 gear oils contain and is safe for the soft metals in the tranny. Additionally it retains the strength of a GL5 gear oil. Max Gear indeed...

I think I'm going to go with Royal Purple. Anyone know if any chains carry it? I'm over here in California, so we've got Pep Boys and Kragen as our big chains.

~ Matt

I ran with redline in diff and transmission for about 25,000 miles. it was much better than stock.

After that I tried out royal purple in both diff and tranny. I can't distinguish any difference when the car is warmed up. But when the car is cold, the royal purple is nicer, as the gear shifts are almost normal. With redline when the car was not warmed up, shifting was notchy and rough feeling.

Nevermind...their website has the info I want.

Click me!

Also, based on the RX-8 manual, it looks like Max Gear is the way to go.

~ Matt

I get the same cold grind with RP (and the stock fluid). It's smoother with RP than the stock fluid: less resistance when cold, and when warm, it's even smoother. To reduce the grind, pause for a split second before engaging the next gear.

check pm

tell em swoope sent ya..

beers :beer:

Hm, sounds like i'll be going with the rp max gear 75w90.

Gonna be putting in my act clutch and flywheel soon, and I wanna kill two birds wiff one stone. Prolly match the brands and stick with rp. Is there a specific type of tranny oil I should look for? Or does rp only offer one.

I should prolly look myself, but..I like opinions.

rp max gear 75w90

does both tranny and dif..

beers :beer:

^heh. Don't I feel stupid?

Oh well, just me being honest.

That's what forums are for, right?

From what I understand the OEM is a synthetic trans oil already and it dose not grind the gears when cold. Makes me wonder if it is worth switching it.

its well worth it.

If yours doesn't grind gears cold, then RP won't either. I basically get same or better feel after switching to RP. It's not worse in any respects.

how many quarts should I buy if i'm gonna replace the fluids for tranny and diff.?

4

Thank you.
:icon_tup:
:smoker:

Switched to redline about 10000 kms ago . Was really looking for an improvement but could not detect any . Mind you I did not buy the car new so who knows what was already in it.
Gear change has always been slick . Only gripe is the whine in 6th - presume everyone has that ?

so 4 qts. is enough for both 6 speed tranny and rear diff?

yes, more than enough.

i think i will do this too. :)

I had my 30k service done and Max Gear 75W-90 put in the transmission.

My first impression was that the shifter effort is considerably lower. Now, after driving around a bit, I've also noticed that shifting into first higher than around 25 mph can create a bit of a crunch, even when rev matching. This wasn't the case before.

One thing I want to try, but haven't yet, is to see how the high rev 1-2 and 2-3 shifts are. I've had problems with the stock fluid in the past where, even with the clutch to the floor, you get a grinding noise when putting it in gear.

Plus: Reduced effort, better "feel"
Minus: Some trouble downshifting to 1st gear
Unknown: Hi-rev upshifts...


~ Matt

downshifting at 25 mph into 1st gear.... are you sure the trouble is not because of the wear you do to it when you do that?

Speaking of this...I switched to RedLine fluids at 30,000 miles and am now nearing the 60,000 mile mark and will be switching to RP (it gets cold up here in WI). What do people think about mixing the leftover RedLine with the new RP? I hate to just pitch half a quart of MT-90 and half a quart of 75W90.

^ should be fine. I didn't do anything special from my switch from RL to RP

Just switched from redline to RP Max-Gear 75w90 for both the tranny and diff at 42k miles. No more hard cold shifts into 1st :ylsuper:

I just changed from Redline to Royal Purple. The Redline was in for a little more than 3,000 miles, but I just didn't how it was crunchy on the 1-2 and 2-3 shift when cold. After the Royal Purple went in, I can say that the shift quality throughout the temperature range is much better. I should've gone with my instinct to go with Royal Purple in the first place rather than get Redline since I wanted different oils for the differential and the transmission.

It seems like I'm the only one, but...my tranny actually feels better and sounds better when it's cold...? I've got the stock fluid (got RP waiting to go in), but the tranny WILL GO INTO GEAR EASIER when its COLD, and the SYNCROS make LESS NOISE when it's COLD!!

But... I grinded 2nd gear at high rpm for the first time yesterday (was properly warmed). Maybe throwout bearing, maybe syncros, or shift fork, I don't know what the deal was with that.

Might be a stupid question, but can I use the 4 Quarts of the RP Max-Gear 75w90 oil I just ordered for both the transmission and differential? If not, anyone in SW houston wanna buy two bottles for $16 bucks? :ylsuper: