The Redline MT90 I've been using overheats with track use. Does anyone have any information on the Shockproof or similar racing oil? Has anyone run it for a while? What is the change interval? Damage to synchros? I know it's GL5 and Redline does not recommend using Shockproof with synchros.

See: https://www.rx8club.com/trouble-shoo...kproof-120874/

Also, any recommendations on diff fluid? I think I'm getting some inside wheel spin.

Thanks,
Chris

 

I've had great experience using Motul products. Might be worthwhile to check them out.

Gear 300 (trans) & Gear 300 LS (diff) in my FC, FD & currently FE.

 

Need more information-

What year gearbox
what makes you think your overheating it


I use MT90 in my race cars and it works perfectly. I would not use Shockproof heavy, as the heavier fluid will actually cause the gearbox to run hotter, not cooler.

 

true that--in the Ga rx8 club and many thousands of track miles--no problems with MT 90 and we all use it.
Of course our on track times are usually no more than 30 minutes at the time.
Now the diff CAN get hot, but trans are usually no problems..

 

Gearbox is from a 2006 ~ 45K miles on it. Shifting gets much more difficult after a few laps (~5-10 minutes at 6500-9000 rpm). It gets much more difficult to shift without grinding, especially on the 3-4 shift. Shift boot is too hot to hold your hand near. Also, tranny feels best to me when cold after sitting. This 'overheating' effect is getting progressively worse with time and was noticeable after just 3 laps on my last event.

I haven't had a look at the fluid yet so won't know for sure until I decide what to replace it with. What is a normal change interval for the MT90? I have about 6-8 track hours since new. I'm getting the sense I should just try some fresh MT90.

Do you guys slow down your shifts a lot on the track? It seems to be the only way to get a smooth shift for me once the tranny heats up. Any videos?

Anyone have experience with using higher viscosity differential oil?

Thanks

 

apparently you have no experience using the Search engine either ...

 

I have searched, I made a link to what I thought was the most relevant thread in the first post.

Here are some older threads:
https://www.rx8club.com/rx-8-racing-...-fluid-176728/
https://www.rx8club.com/tech-garage-...-fluid-127253/
https://www.rx8club.com/trouble-shoo...ebuild-123305/

From what I can tell, you preferred the Redline 75W140NS? Is it still working well for you?

Another theory: These tranny problems occurred at the same time as my cat clogged, could higher local temps be to blame?

I can't find any good information on change intervals or adding a more viscous oil to the diff.

 

Your exhaust is heating up your trans and everything else around it, if you have a cat and are using it on track thats just bad.

The hard shifting is because you have an 04-09 trans and its getting hot as hell, and the plastic parts inside are melting. Speedsource had a fix for this with replacement metal parts for the plastic bits. You very likely need to have the trans rebuilt at this point. There is nothing good about tracking a car with a cat, especially a clogged one that is superheating everything.

You need to change the gear oil. Now. As in this evening if you have it on hand or tomorrow if you can steal it from a friend. I change gear oil every second or third race, but thats just me, others leave it in all season.

You do not need more viscous fluid in the trans, nor do you want a heavier one. You need to remove or repair the actual problems.

You likely need to use Redline Lightweight Shockproof in the rear diff, and MAKE SURE the exhaust is not overheating it as well. We have had to use heat wrap etc to control temps here.

The 04-09 trans is junk and will not live a very long life in racing, and I doubt its much better as a daily driver/trackday application. A heavy handed or intolerant driver can and will destroy the trans in a few sessions. The 09-up hearbox is the solution. It drops in (you will need the correct shifter) and is a very strong and reliable transmission. It is relatively reasonable at about $2500 last I checked. (NOTE- I could be off, I buy through MAZDAs Pro program which has some discount)

 

^^ in other words, you have no direct experience on using it

 

I have a lot of experience using Redline Heavy Shockproof Gear Oil, however the RX-8 gearbox is not an application where this should be used.

Since we are on the subject of gear oils-

I use Liteweight Shockproof in the rear diffs, it works perfectly and we have no issues. One car does have the trans cooler, the other does not.

These#7 car used MTL when the previous owner ran it, but MT90 works better. If we were to have issues the 75/90NS or similar might be a good solution, but we dont have issues at this point.

Liteweight shockproof is an OK option if the synchros are already a bit damaged, and a little friction modifier can be added if needed. BE WARNED too much friction modifier or too heavy a gear oil is bad.

I can think of no legitimate reason why you would want to use Heavy in an RX8 gearbox. Yes, the added sulphur etc. will "slick" up a box short term, but the reaction to the brass synchros and friction surfaces is not going to be good longer term.

I have also had extremely positive results with Enoes Gear oil, which while it has the properties of a 75/90 gear oil it pours like 10weight oil. My concern is that it might be too "slick" and might need a friction modifier added.

Motul makes a good gear oil, but I prefer Redline products

No RP products are to be used in my cars.

JOE GOBBD DRIVEN gear oil is made by Valvoline to JG specs and is pretty good stuff. It it was as available as Redline we might use it (I believe Eric Meyer used Joe Gibbs gearbox oil in his cars)

 

S1 transmissions won't last long no matter what you do to them. The only thing that helped was a transmission cooler with an electric oil pump.
Given the temperatures I see on both s1 and s2 transmissions I use red line 75w140 oil and keep an eye on tranny temps. It's common to see temperatures above 140°c...

However they may be a better solution than the s2 transmission gearing wise with the same final gear (4.777 or 5.125). There also are many upgrades available for aisin AZ6 boxes but they are well above an enthusiast's typical price range.

I have found the s2 gearing to be horrible with a 4.777 final gear and it will sure be too long for a stock car with a 4.44 R\P.
A 2500$ box quickly becomes a 4000$ project.

 

Three years with it in my current transmission is to date the longest life I have gotten out of one and its still going strong. Apparently that must not be long term enough since I have never seen what you claim regardless. It is no heavier/viscous than a standard gear oil either. You are talking theoretical assumptions and guesses out of your tailpipe again just like you did about using 0-20W50 engine oil previously. Telling us what you do does not make you an expert on what you haven't done. Let us know something useful after you actually do it for once ...


.

 

How many hours in those 3 years Team?

 

How many hours at the track Team?
How hot does the gearbox get?
How long are you at speed?

Im sorry to remind you, but driving around on the street and autocrossing is not the same as being on track for any length of time.
Heavy pours pretty much the same as a regular gear oil, but it does not react to heat the same, so I think your the one who needs to step back here and not talk out his tailpipe based on his singular experience in a rarefied application that does not parallel the fellow who asked the question.
And of course your right, I do not know about dodging cones in parking lots much anymore, thats very true, but I have broken enough of these gearboxes to know what I am talking about. I also have a very solid understanding of the heat issues of an rx-8 engine, transmission, and diff on a track at speed.

Now, FWIW back when I got the 8's I spoke with an engineer at Redline about fluids they recommend for the 8, because I had conflicting information between what I thought should be used (M90) and what was being used (MTL), as well as diff and engine oil. Their specific recommendations were MT90 for the trans, Liteweight in the diff, and 30wt race oil for the engine. These recommendations to me were based on what they see at the track, reports from teams using the products, and thier own testing. Redline does not recommend Heavy in this application at all, and they I assure you are not talking out of thier asses and do know a bit more than you or I about gear oils.
Now, I did not blindly follow their recommendations, we tested the MTL, MT90, 75w90NS, MTL with friction modifier, MT90 with friction modifier, Litewight, Joe Gibbs, and Swepco in the transmissions at the track (sorry, no street use) and ended up using the MT90. As a note, I liked the Joe Gibbs MTF, and I know Meyers was using it, but I stuck with Redline. Swepco is also very good stuff, but might be a bit hard to find out in the wild. Should be noted that Since we travel a fair amount we tend to use what we feel can be found at most tracks or close by most tracks, so thats also a factor.


Super glad its worked out for you, but I have used Heavy in similar applications and its not been good results.

 

My plan:
Get a high flow cat or midpipe - need to do some research here. This is a DD and don't want any rotten egg smell.

I am going to try some fresh Redline 75W140NS in the trans and some Redline 75W90 in the differential.

If inside wheelspin (I run stock height because its a DD in MI) is still a problem, I'm going to try some of Redline's LSD friction modifier.

Unless anyone has some good evidence against this combination, I'm going forward and will report back after some track time.

Thanks for all of the advice.

 

Chris,

Burned up both my cat and the S1 tranny when i started tracking alot.

Buy a high flow cat. We then cut out the cat part and made a straight pipe section that we could slip in and out with VBands. This give you the option to be straight pipe when on the track, and still run autocross with a cat and minimal smell. I can send you pics if you want.

I run the S2 Tranny now with a 5.12 (race) ring and pinion.

Don, I'm curious. Does that oil recommendation change with running a Sohn adapter to burn marine oil instead of oil from the pan. Eric Meyer and I run 20W50 since we don't have to burn oil from the pan. In this summer heat, that seems logical since it doesn't have to go through the oil injectors. I drop down to 10W40 in the Spring and Fall. Curious on your thoughts.

 

I do not use the sohn adaptor on my race car anymore, although I do recommend it for most people. The problem I have with the Sohn in my application is its one more tank to fill(or forget to fill) and it adds weight, both of which are an issue for me.

With the 30wt race oil the engines I have torn down have shown no significant wear, and have experienced only 1 engine failure (at mosport, not yet torn down for analysis). 20w50 is just too heavy IMHO, and I would not run it, injecting it or not, summer or not. I have no opinion on what others do or do not do concerning oil. I can only state that oil in a rotary has many roles, including cooling, sealing,and lubricating. There is no need for a multi-viscosity oil because the car is always warmed up before being driven. However, if I were to use a multi-viscosity oil it would likely be something in the 0-30 0-40 range. Eneos 0-50 might be an option.

 

Have a check on the Diff temps and you likely will quit worrying about the transmission oil

I ran for 20 min yesterday in 90 deg ambient temps to test my tranny and diff coolers....

With the pumps and coolers off....after 20 min the tranny temp was 257 degreees....and the diff temp was 360+.........way too hot for anything to survive for long

Pumps and coolers on and they both stayed at a nice 200-210 degrees........

I was shocked when I put the temp probe in the diff and transmission....

My stock diff used to get hot...but it seemed to level off in the 340-50 range...but I was slower then..and didn't run as hard for as long

4 hours on Friday and neither had a temp spike at all. I have the fans on a temp regulated switch and I am always shocked that by the end of the cool down lap they are off. I thought at first that they weren't working properly...so I took the rear end off the car to get to the thermoswitches and used a heat gun to warm them up....and they came on regular as rain. If I stop in the hotpits they are on....by the end of a cool down lap they are off.....

I'm a happy camper...one of my best mods yet

 

Doc,

Thanks for the recommendation. I'm going to look for a straight pipe for track and use the stock cat for street. I don't autox too much and am not too worried about it; I just leave it in second anyway so the RPMs are usually low.

 

You should look for some 2 stroke oil designed for an air cooled application. Yamalube, Rotax or Idemitsu etc....are much different than marine oils that have been designed to run at much lower temperatures, and have environmental constraints with being introduced into the water

 

We are using the Redline heavy shockproof oil in the rear diff. To be honest we DO have a temp gauge hooked up to the lower drain plug and within 20 minutes it is pegged. (As you know a standard Diff guage reads to 250...) We have taken every measure to keep heat away from the rear diff. (Heat wrap, specifically designed to stay as far away as possible, ect) We are running a 5.12 in it so the thing is spinning mad fast, so without a cooler it is going to get real hot real fast!

In the transmission we use the Redline MT90 and we do not have issues. Hoever i will be honest that we do NOT have a temp guage hooked up to that yet. I will try to do this for later this year to let you know what I am getting for temps.

cwatson, you said it was overheating... but I don't think you have a gauge hooked up to it so I assume it was your opinion based on the issues you described? Not trying to bash on you just trying to understand if it may be something else and not in fact a fluid issue. Later on in the thread you talk about wheel spin. Is it only turning one direction or both? lots to explore here and likely a set-up issue rather than a fluid issue.

Stephen

PS: Redline has lots of great info on their site. They also specifically say not to use Heavy shockproof in a syncro transmission.

 

Stephen,

I surmised it was overheating because all ill effects occur once the transmission is hot. I do not have temperatures and have not yet seen the oil, so I could be wrong.

I believe I am getting some inside wheel spin (forward) in tight corners because the revs go up but the velocity doesn't and the rear does not come around. I've driven cars with high TBR (4-10:1) and spools so I know the feeling. On the other hand, I recall now that I was once finishing off some tires and had no problems getting two black lines on concentric circles (at relatively low lat g though). Thus, I have no conclusive evidence for the IWS but was wondering if anything can be done if it did exist.

Car set up is 1.9-2.4° front camber, 1.3-1.7° rear and slightly stiffer rear bar. Toed straight in the rear and out in the front. Stock springs/shocks. Very slight O/S once everything is heated up.

Also, if anyone (that doesn't destroy transmissions) has track videos with a clear engine note or the shifter in view they would be great to see for reference.

Thanks,
Chris

 

The series 1 transmissions are supposed to be "fragile"....I must have gotten lucky..

I have over 30 track days on mine and 65K miles street driving...high temps for the first 3-4 years before I put in temp guages and got a huge shock...

I have 2 spare transmissions cause Mark kept breaking his ...Never used them. I don't autocross though..and I think the shock loading in that application is very severe.

My personal feeling is that without an error...they are strong...they just don't like ham handed and rough shifting with poor gear matching. If you try and slam them into gear they will break....if you slow down your shifts just a touch and rev-match it should last just fine.

Don't get me wrong....I have ground enough syncros missing shifts.. I have installed one of Scotts sysncro savers ( RX8performance.com) years ago and they seem to help

Like I said...either that or I got a really good "tuesday" unit

 

I do not use marine oil. I use Redline Racing Two stroke oil. I have no experience with marine applications, although I do own a 1973 Suzuki GT550 three cylinder two-stroke triple, which is aircooled and oil injected... it even has a tiny OMP regulated by the throttle much like an S4 FC...

 

Toe in will help in the rear, a stiff rear bar might actually be hurting. Some have removed the rear bar completely.

I have lots of in-car video and will be placing it online soon.