Some of you may be aware that I was struggling with a very loud grind when I shifted from 3rd to 4th while the RPM was over 5000.

I had been using Royal Purple prior to the problem starting and I had a full flush done with Royal Purple and the problem persisted.

A few people suggested that I try Redline MT90 and to my surprise the problem disappeared immediately. At the last track day the gear change was back to normal.

So now I am a happy camper and recommend the new product.

skc

 

Was that in the tranny or the dif or both?

I had the same problem at wakefield coming down the straight when I shifted into 4th I got a grinding.

 

I just changed the Tranny fluid. The diff was changed just prior to the nats with Royal Purple.

skc

 

Just about every 9/10 people on this forum started grinding when they started using Royal Purple in their transmission.

It's OK to use Royal Purple in the differential.

 

I don't think it's that simple. I think most people see an improvement with rp. It took several years before the synchros were toast and grinding to occur. Even then my symptom was 2-3 upshift. Mazda initially wanted to rebuild, but when they cracked it open they found it wasn't rebuildable.

I use rp in engine oil and diff still. Will never use it in transmission again.

There may still be rp appoligists out there, or people who claim user error caused it - but over time with more and more transmissions being damaged while using rp, they have decreased in number.

 

Fark. I'm glad I read this.

I've been using RP in the gearbox and diff without any problems but will change it now. I wonder why it causes gear damage??

I'll get some Redline put in next service...

 

I started using RP about 18 months ago. About 3 months ago I had the transmission oil flushed and the technician commented that it was extremely dirty and had metal shavings. I found this odd since I had used the car for over 2 years prior to the first oil change and they did not find as much deterioration.

I started having doubts about RP after this incident. I am glad others have come forward and shared their experience so this simple mistake is not made again.

So far the Redline oil is doing its job and after one track day it seems to be holding up. I hope I have not done serious damage to the gear box.

skc

 

It's been explained elsewhere on the site that RP is a GL5 lube, whereas Redline is a GL4. GL5 oils are harmful to the soft syncros. This takes a while to show up.

 

Will the use of RP have a lasting effect on the transmission? May be I should do a full flush with Redline.

skc

 

Read the following two threads, search for others, then make your decision.
https://www.rx8club.com/series-i-tech-garage-22/royal-purple-tranny-rear-fluids-fail-178499/
https://www.rx8club.com/series-i-trouble-shooting-95/trans-grind-after-royal-purple-ordered-redline-shockproof-120874/

 

Thanks for taking the trouble to post those links.

Irrespective of the people who haven't had problems, it's just not worth the risk to be bloody minded about it. I'll change out the RP and put some Redline in asap.

Hopefully, my synchros aren't too far gone...no grinding noticed yet.

 

When I first had the problem the initial oil change with RP did not help at all therefore I am convinced the PR was the cause of my problems. Once I changed the oil the problem disappeared instantly.

skc

 

Well, I'm bloody glad I changed that RP out. Mechanic did it today and just gave me a call.

From memory I've had it in the gearbox for less than 10-15k kms (I'll check the correct mileage when I get home but it's under that) and he said it was blacker than midnight and stuffed.

Redline MT90 is now in, with a spare two litres for another change. Says it last 200,000 kms on the bottle but bugger that - I'll change it out before it hits 50k I think.

Btw, it's not cheap and hard to source. Mechanic had to get it from WA! Anyone else had a problem sourcing it here?

 

Edit:

I've got over 25,000 miles on GL5 and not a single grinding issue like that.

Honestly, this is an urban myth and anyone who claims otherwise has yet to offer any proof of syncro destruction because of the fluid.

If RP actually caused synco damage then the grinding would continue despite any fluid changes. In nearly every case I have seen or read about the grinding issues would cease once the fluid was changed.

 

Dave,
I have had Redline MT90 for about 16K (10K Miles) and it was bloody smooth, but is has lost a bit of it's lustre and as Andrew says in his opinion it is best to change it about every 20K, certainly not 200K..and I agree, I am going to renew in about 2K.

My first consignment I got from WA, it is cheaper from the east coast though...there is a good on-line supplier in Victoria..

http://www.performancelub.com/Redline%20pricelist.htm

Have used him and very good...

 

BTW...I can not understand why anyone would use a GL5 Oil in their Transmission when the factory (Mazda) have said from day one ONLY use a GL4..

GL5's are OK for your Differential though..

And yes I know some have used "other" brands of GL5's in their tranny with No issues, but why take the risk?

 

Mazda also says to use 5w-20 in your engine but we've seen how well people have taken to that.

You can't have it both ways...either you trust what Mazda says or you don't.

As for why take the risk...myself and the people I work with are in the business of taking risks. All of us at BHR ask the question "why do it that way?" all the time.

Doing something simply because it's always been done that way only lends itself to being left behind.

The GL5 stuff I've used produced the smoothest shifting and ease of gear changes out of everything I've used. I've used ALL of redline's product line, Royal Purple and even Mobile1's stuff and the Eneos performed much better in my transmission. I'm not the only one to claim that as many others have said the same thing.

Don't worry, if my transmission falls apart cause of the stuff I'll be the first to fess up to it. However after 25,000+ miles if there's any damage it's because of shifting mistakes made by me and not the fluid.

 

Good to hear, next tranny oil change I will try the Eneos.

 

No matter what people say my gear shifts are as smooth as new now that I have changed to Red Line. I do not drive any differently on the road or track before the change. However with RP I had to cringe each time I changed from third to fourth.

I have had a couple of track days since and I can change gears with confidence in the heat of battle.

During the oil change the Mazda dealer also reported an extremely dirty oil when I had RP in the gearbox.

skc

 

I have the redline Shockproof light in my gearbox and redline shockproof heavy in my diff. Are these the redline oils you guys are using?

 

I did not get to the point of grinding but I was surprised that the oil had degraded so badly so quickly. And my initial impressions (not including a track day yet) are that the change is smoother and faster with the Redline.

Your logic seems sound and this may well be myth but for the cost of an oil change I'd prefer to retreat to a GL4 and leave it up to risk takers like yourself to push the boundaries.

 

Thanks Ash. I was surprised by the 200K recommendation. I'll follow the 20K plan too I think.

Thanks for the Vic contact.

 

MT90 Matt. Taka uses the Shockproof...

 

I use the MT 90 as well

skc

 

Rx8 has to use a GL4 gearbox oil OUrs syncros are not bronze, If you use a GL5 oil , it contains sulphur (thats the bad smell of rotten egg gas in your Redine shockproof oil Taka), and this is corrosive to the syncros, and they will wear out more rapidly. Redline MT90 is fine, and most people using it appear happy. RP is not recommended as it is a GL5 oil.