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So, having my gearbox out at present I have made a nasty discovery. The Redline oil I have been using for the past 100,000ks apparently over time forms into a thick grease around the various seals in your box, and in my case has pushed its way past the front and rear seals in the box. The clutch guys who pulled the box out pointed this out to me and commented that they have rebuilt boxes from WRX's and Evos that had been running this oil. Their comment was that it was great for improving gearchanges etc, but crap at cooling bearings, so not recommended. I have asked them to open my box and flush it out then replace it with Castrol synthetic. Shame, it really did improve the change, but no good if it stuffs seals

Did they say anything about MT90?

They were pretty unimpressed with the whole range Dave; best thing to do is pop the gear lever out and run your finger round inside the turret - if you come up with a greasy residue then I would ditch it before your seals start to leak....

How do you flush all the gunk out?

You could probably just run with some cheap fluid for a few days, and then flush it all out. That might flush most of the gunk out, and then you are ready for some decent stuff.

I must say I am a bit worried about this, im running MT-90 in my gbox.

Damn, I just got Redline Shockproof put in, I guess I'll have to monitor it and see how it goes.

Out of curiosity how often did you change the oil?

Mr Starlet would have to agree with your sentiments BigDog.
Rear gearbox seal leaked.

castrol syntrans is what i use and its quite good. shift feels nice enough.

BD, how did the gearbox mob differentiate sepage caused by the lubricant as opposed to age/km of the seals.

Perhaps the work life of the lubricant might not be 100k as advertised, therefore surpassing it may cause the lubricant to breakdown and affecting the seals.

It would be interesting too hear redline line's responce.

Perhaps its just me, if seals have lasted 170 clicks without leaking; it seems pretty damn good.

Bigdogs explanation from the gbox guys is hardly an endorsement especially since they also mentioned other experiences. Whether this is correct may never be proven and a proper analysis is not likely to be undertaken. I take the view that changing oil in line with the manuf recommendation is probably wise.

Hi Bigdog, my gearbox guy reckons the opposite and perhaps I have a reason why. We have just pulled my race box down for another rebuild and I specifically asked him about the shockproof and his recommendation. He was pretty happy with it and recommended I continue to use it based on the wear (or lack of wear) in the box. The difference being that my box has never had another oil in it as it was rebuilt before I ever put shockproof in it. Perhaps the makeup of shockproof is incompatible with the residual oil left in the box when changing oil. As for leaks, I have not experienced any from the gearbox seals - but they get changed every time the box is out too. Food for thought.

I suspect you are right CT. If you only ever used redline it would most likely be fine. The problem of residual oil is not easily over come without removing and splitting the box and cleaning it out properly. More frequent changes may also solve the problem (I have been putting off changing it till I dealt with the clutch). Most workshops are opinionated about different products based on negative experiences, so I tend to take them with a grain of salt, but the grease build up was readily apparent in this case. Seal life in gearboxes? no idea, but I doubt they would have leaked without the build up behind them. Anyway, I will play it safe and go back to Syntrans.

Thanks for the heads up Bigdog
Cheers
Old Dude

My gearbox was clean as a whistle after 3 years of Redline MTL or MT90 on annual changes after replacing the original sludge. It just needed new bearings because of age (180,000km) and general operator abuse. No leaks.

As with CT, my gearbox man said he wanted it refilled with nothing but Redline.

I used Syntrans for a brief period (like I think 3 days) and flushed it out because the box was virtually unusable. Baulked everywhere - I could hardly select any gears.