times come to fill the trans with fluid, and was reading up on gl4 fluids, and cant find any really in 75w 85 like nissan reccomends without mixing redline mt, and mt-90. has anybody used castrol syntorq, which is also a factory mopar/gm oil? its 75w 85 and i had previously used it for my evo's mr trans and worked wonderfully, no grinds, super smooth. just seeing if anybody has any experience with this and their input

 

just picked up 4 qts yesterday. gl-4 in 75w 85. not cheap, cost $110 for all 4 so i hope it works! ill test it out and perhaps we can use my application as a test bed for this so we can get some alternative fluid possibilities

 

redline has MT85 now. MT90 presents no problems though. you will not notice a difference between the two.

 

Good info. Planning my flush next month or so when I get my clutch.

 

I just bought redline mt-85 for mine..

 

anybody run shock proof or anything? used this in my evos transfer case and diff, was great. currently running eneos fluid in both z's rear ends.

 

DO NOT put shockproof in your transmission. I could launch in to a litany of all the reasons why but I'm cooking right now. DO NOT do it. I've taken apart or built somewhere between 1500 and 1800 transmissions, transfercases, and rear diffs in the last 5 years mostly for racing and high performance street use, and I am saying this from that experience (and from the experience of my boss who has been doing this for like 18 years, and doing it better than virtually anyone else in the country).

In the Z's rear end shockproof is fine. Anything with synchronizers - don't let shockproof anywhere near it.

 

yea no shockproof in my trans or anything, but thank you for the heads up. any reason behind it??

 

the long and the short of it is that the paraffins that are suspended in the fluid will centrifuge out and gum up every goddamned part in the transmission. this is problematic for a couple reasons.

a) when the paraffins centrifuge out of suspension in the fluid, the shockproof fluid just lost the exact properties you put it in there for. those particles are what gives shockproof it's name. so the fluid isn't providing you any shockproof benefits anyhow after a couple thousand miles.

b) those paraffins have the consistency of peanut butter (seriously, it's nasty. I've taken apart tons of transmissions with shockproof in them and it's quite a nightmare). they gum up everything. they gum up your synchros, they gum up the insides of the shafts (which have oil passages in them, and you don't want to be clogging up oil passages), they gum up the inside diameter of your sleeves (couplers), etc.


So basically there are two scenarios -

if you DON'T change the fluid often all this gumming up probably will not cause much of a problem (because not a whole lot of paraffins are present in the fluid), BUT you also won't be getting any benefit of that shockproof fluid after a few thousand miles. so it's pointless to even put in there. it's no benefit, and it might even be a little bit detrimental.

if you DO change the fluid often, like every 5k, then you will get the benefits of the "shockproof particles", but you will eventually end up with a transmission that doesn't want to work because the synchros are all gummed up, and perhaps parts of the transmission actually getting damaged because the oiling passages to them have been blocked off. we all know how sensitive these transmissions seem to be to synchronizer issues, so I'd keep anything that could compromise their operation far, far away.

The only application I would ever recommend putting shockproof in is a trans that is basically for a race car. a trans that does not see very many miles at all. otherwise it's at best pointless, and at worst damaging to your trans.