Redline lightweight shockproof.

[TXSquirrel]

I rarely shift at above 7000 rpm, but so far I feel MTL shifts slightly quicker than MT-90.  That could all just be in my head though as knowing beforehand MTL is rated at 75W-80 and MT-90 is rated at 75W-90.  

[GTSBoy]

3 hours ago, TXSquirrel said:

That could all just be in my head though as knowing beforehand MTL is rated at 75W-80 and MT-90 is rated at 75W-90.

It is in your head. The viscosity difference at operating temp is 3/5 of f**k all.

[TXSquirrel]

Maybe someone else can try MTL out and report back.

[BK]

On 24/01/2021 at 12:11 AM, MoMnDadGTR said:

redline shockproof fluid is total junk.

FYP, more correct. If shockproof was so good for gear only protection the offroaders with Albins dog boxes would use it - they do not.

Shockproof is a funny one. For more clarity regarding this, as Duncan mentioned if you use it with a stuffed synchro box it masks the problem with shifting. But from my usage from years ago if you use it in a great condition box it stuffs the synchros - go figure.

On 24/01/2021 at 5:00 AM, TXSquirrel said:

I had MT-90 before but running MTL now.  I prefer MTL, seems to suit better with the warmer and more humid climate I am located.

Redline MT-90 or MTL seems like a good choice if it's readily available to you for sure 👍 The difference between then might not just be in you head though-

Because of availability, I just personally have found the synthetic Castrol Syntrans 75w85 to be the best with synchro boxes for shifting quality. The  Penrite equivalent (which the name escapes me) is also pretty good.

Castrol Syntrax 75w90 by comparison was total crap - no shift above 6000rpm, so I think it's more to do with the contained additives sometimes not just the viscosity.

Syntrans is a GL-4, Syntrax is a GL-5

[Butters]

I am running TriboDyn in all my gearbox's now and so far working really well. 

Quietened down a gtr box with noisy bearing and it didn't like to shift great when cold.  It has saved me from pulling it out and been going 2 years now. 

Also going fine in my syncro OS giken box 2years later. 

 

 

[MoMnDadGTR]

5 hours ago, BK said:

FYP, more correct. If shockproof was so good for gear only protection the offroaders with Albins dog boxes would use it - they do not.

Shockproof is a funny one. For more clarity regarding this, as Duncan mentioned if you use it with a stuffed synchro box it masks the problem with shifting. But from my usage from years ago if you use it in a great condition box it stuffs the synchros - go figure.

Redline MT-90 or MTL seems like a good choice if it's readily available to you for sure 👍 The difference between them might not just be in you head though-

Because of availability, I just personally have found the synthetic Castrol Syntrans 75w85 to be the best with synchro boxes for shifting quality. The  Penrite equivalent (which the name escapes me) is also pretty good.

Castrol Syntrax 75w90 by comparison was total crap - no shift above 6000rpm, so I think it's more to do with the contained additives sometimes not just the viscosity.

Syntrans is a GL-4, Syntrax is a GL-5

 Castrol Syntrans 75w85 for the win. i messaged you a while back on this ben,  was able to get a few rips in the car with the new castrol fluid before we ripped it apart for the build. shifted the exact same as the fluid i had in prior at regular rpm(3-5500) but seems to be far better at redline shifts...this is just my opinion tho, im not an expert by any means. but i do know for a fact that i have thrown out 300 dollars worth of redline fluid this week. 

[MoMnDadGTR]

they should call it deadline cause thats what your synchros will be when the fluids done with them...dead

[BK]

1 hour ago, MoMnDadGTR said:

 Castrol Syntrans 75w85 for the win. i messaged you a while back on this ben,  was able to get a few rips in the car with the new castrol fluid before we ripped it apart for the build. shifted the exact same as the fluid i had in prior at regular rpm(3-5500) but seems to be far better at redline shifts...this is just my opinion tho, im not an expert by any means. but i do know for a fact that i have thrown out 300 dollars worth of redline fluid this week. 

Hey that's really good to hear you've had good results with it too. At lower rpm shifts any  gear oil will pretty much feel like anything else I guess when at operating temp, but at higher rpm is where you'll generally notice the difference between different oils.

I've tested heaps of these different oils on the quarter with the GTR synchro stock box and the OS giken synchro box which means shifting at least at 6.5k - 7k plus. The Castrol Syntrans 75w85 is completely repeatable at a variety of different temps on high rpm shifting - really really consistent and never broken a box with it (touch wood).

I've broken gearboxes with Redline shockproof oil, HKS actual GTR specific GTR gear oil and Castrol Syntrax 75w90.

The HKS oil is another one to avoid as it seemed just too thick for the synchros to work properly. I think it was a 90w120 from memory and I'm not even sure if it's sold anymore. But the Shockproof lightweight, HKS and Syntrax oils hated the 2nd to 3rd shift - they just didn't go in at speed.

[MoMnDadGTR]

1 hour ago, BK said:

Hey that's really good to hear you've had good results with it too. At lower rpm shifts any  gear oil will pretty much feel like anything else I guess when at operating temp, but at higher rpm is where you'll generally notice the difference between different oils.

I've tested heaps of these different oils on the quarter with the GTR synchro stock box and the OS giken synchro box which means shifting at least at 6.5k - 7k plus. The Castrol Syntrans 75w85 is completely repeatable at a variety of different temps on high rpm shifting - really really consistent and never broken a box with it (touch wood).

I've broken gearboxes with Redline shockproof oil, HKS actual GTR specific GTR gear oil and Castrol Syntrax 75w90.

The HKS oil is another one to avoid as it seemed just too thick for the synchros to work properly. I think it was a 90w120 from memory and I'm not even sure if it's sold anymore. But the Shockproof lightweight, HKS and Syntrax oils hated the 2nd to 3rd shift - they just didn't go in at speed.

i usually drive my car at night time around here so i know i sound like a classic dumb canadian but its cold here always(about 0 to plus 15 degreees celcius here all summer and fall. minus 52 today no joke coldest day of the year today i think. cant even go outside it f****d out, so even getting fluids to warm up daily driving can be a challenge. especiialy on our diesel motors. this being said i felt the hotter and harder i was on the syntrans fluid and the more i got the gearbox temps up it just started shifting like a dream. im totally convinced i wont use anything else now. i think anyone using redline is either stuck in the 90s or still using USA forums for information. real smart......

[MoMnDadGTR]

drove the sti this morning 4 blocks to day care and went and got mail, by the time i got home i would have to wait about 2 seconds for the clutch slave to fully disengage before i could get back into throttle and continue into the next gear. fluid turns to gel fast....im ready to move soon

[TXSquirrel]

9 hours ago, BK said:

Redline MT-90 or MTL seems like a good choice if it's readily available to you for sure 👍 The difference between them might not just be in you head though-

Because of availability, I just personally have found the synthetic Castrol Syntrans 75w85 to be the best with synchro boxes for shifting quality. The  Penrite equivalent (which the name escapes me) is also pretty good.

Castrol Syntrax 75w90 by comparison was total crap - no shift above 6000rpm, so I think it's more to do with the contained additives sometimes not just the viscosity.

Syntrans is a GL-4, Syntrax is a GL-5

Under 4000 rpm I know the difference is definitely not just in my head, MTL shifts way better than MT-90 especially before fluid is fully warmed up and that's why I prefer it.  Between 4000 and 7000 rpm the difference is interesting, it's hard to describe but kind of feels like stirring different viscosity drinks in a glass with a metal spoon.  The MTL feels like stirring a more watery drink in a glass so I can move the shifter quicker, but the moment it goes into gear there is a slightly crispier but harsher notch, like clinking the glass with a metal spoon in coffee instead of smoothie, a feeling I'm still getting used to.

With MT-90 the 2nd gear would grind before completely warmed up, and I switched about 6 months ago because a shop suggested MTL could help and the job was inexpensive.  Will see how it holds up in the next few years.

I believe you are right about the different fluids containing different additives and not just difference in viscosity.  Your experience with the Castrol fluids could be comparable to my experience with Redline fluids, and I'm interested to know if others would like to try it, however sounds like Redline isn't as readily available there.

[MoMnDadGTR]

17 minutes ago, TXSquirrel said:

Under 4000 rpm I know the difference is definitely not just in my head, MTL shifts way better than MT-90 especially before fluid is fully warmed up and that's why I prefer it.  Between 4000 and 7000 rpm the difference is interesting, it's hard to describe but kind of feels like stirring different viscosity drinks in a glass with a metal spoon.  The MTL feels like stirring a more watery drink in a glass so I can move the shifter quicker, but the moment it goes into gear there is a slightly crispier but harsher notch, like clinking the glass with a metal spoon in coffee instead of smoothie, a feeling I'm still getting used to.

With MT-90 the 2nd gear would grind before completely warmed up, and I switched about 6 months ago because a shop suggested MTL could help and the job was inexpensive.  Will see how it holds up in the next few years.

I believe you are right about the different fluids containing different additives and not just difference in viscosity.  Your experience with the Castrol fluids could be comparable to my experience with Redline fluids, and I'm interested to know if others would like to try it, however sounds like Redline isn't as readily available there.

i dont know why you would ever select a fluid based on how in functions when its not at operating temps. id be more concerned about how it when being smacked around a bit and what your synchro's look like when you tear your gearbox down... just my 2 cents tho. sounds like your pretty easy on your unit and dont rev it up to often tho, so i bet you could pretty much through wat ever you want in there and you would be ok. cheers. i dont think its hard to see that most the guys here commenting are running way more power than me and you ever will and they are saying its not good. if you took that redline fluid to the track for few days your gearbox would look like it has grease in it. b interesting if you magically had some syntrans and could try that. i feel like this thread would be dead at that point.

[BK]

Remember the Redline MTL and MT-90 are not shockproof oils, they sound like they might be ok.

[joshuaho96]

If your transmission lives a pretty easy life and isn't subject to heavy shock loads then protection at operating temperatures is not as big a concern as behavior when cold, personally I plan on trying Motorcraft's GL-4 as it supposedly has had pretty good results at taming some rather grind-prone Miata transmissions.

[True Slide]

I have a neo but regular r32 gts trans, i rebuilt it and switched from mt90 to heavy weight shockproof. Stuffs great.

[alexj]

So here's an odd one that I'd like to hear opinions on.

I ran a standard r32 gtr 1991 5 speed on track for years. it had heavy shockproof in it that whole period. No problems at all.

I bought a brand new series 3 box from rhd and my garage put "normal" oil in it. It ran fine for a few track days and changed the oil.  now after around 5-10 days on track it crunches on all upshifts over 4500rpm or so. Only double de-clutching stops the crunch on high rev changes.

When it started crunching I got the garage to inspect the clutch (os twin plate) and bleed the master and slave cylinders. They couldn't see anything wrong.

What killed the new box, wrong oil? The first fill on the new box and the oil change were both Millers CRX 75w90 NT which are described as for "Manual transmissions, synchromesh ... which require API GL4 or GL5 performance"

Edited August 19, 2021 by alexj