Welcome to the SR20 Community Forum - The Dash.
SR20 forum logo

Thread: LSD Box + MT90 = Bad?.....

+ Reply To Thread
Posts: 1-10 of 31
2009-11-24 19:46:10
LSD Box + MT90 = Bad?.....
I recently swapped the oil to MT90 in my lsd box, since then the box has started whining and the diff has become quite clunky at low speeds..... the whine is quite prominent in 3rd and 4th...

I had to change the clutch and flywheel 3-4 days after changing the fluid, so it was drained again, shafts removed etc

When I drove it and first heard the clunk I assumed driveshaft, got the car up on ramps, had it all checked over and everything is snug and tight.... there was a little bit of play noted in the passenger side shaft (your drivers shaft) but it cannot go into the box any further....

Ive just read about 20 threads praising the MT90 fluid has anyone had any bad experiences with it??? could the fluid be the cause or has my diff lunched itself?? or even worse my box??



too much play?
2009-11-24 20:09:24
What were you using before?
I have always had great luck with MT-90 over the years.
I dont think it caused your problems,may be coincidence?
2009-11-24 20:12:45
I have found the mt90 to be rather thin and give me notchy shifts. Never got any whining or anything though. I used some napa gear lube 85w-90 and boy did that thick stuff feel good. Until it got too cold out.
2009-11-24 20:17:47
Its been my experience that it seems every time ive used MT90 or any of my friends using MT-90 that they have nothing but problems and have broken trans, had bearings go out. Had shifting problems. I have used Redline Lightweight shockproof and it worked very well for the time i used it.

But now i have used nothing but Mobil 1 75-90 synthetic gear oil and again ive never had any problems with shifting or bearings but have broken gears which can be expected with nearing 500whp.

Now i have done even more research and also in the Honda Community a lot of big drag people are using Penzoil Syncromesh in their trannies. It has sheer resistant additives althought its very very thin stuff it seems to be holding up and making shifts like butter.

So i gave it a shot in a friends B15 trans that he was having grinding issues with 3rd gear and really notchy shifts. Sure as hell the grinding went completely away and shifts were like butter. The only thing he has noticed different is the gears whine a bit lounder than before but nothing serious. Its just slightly noticable. So i think from now on im using Penzoil Syncromesh and gonna give it a try in my P11 trans going in. We will see if it can hold up to the abuse and i definetly could benifit from the smoother shifting when drag racing.

I will let you guys know
2009-11-24 20:26:19
the mobil1 is suppose to be bad for our trannies but you are the second person I know of that runs it with zero issues.

The syncromesh is suppose to be very good stuff and is what I'm going with next time I have to swap out.
2009-11-24 20:33:03
yeah i have been using it in every trans i have used in the last 2 year which includes friends trannies as well. Shifting is good but not near as smooth as the Syncromesh.

So far i love it plus its significantly cheaper than mobil 1 haha
2009-11-24 20:48:24
Many of us have modified enthusiast cars with an unknown history and/or hard life as currently driven. The failure rate of the stock gear set is well documented.

There's nothing wrong with Redline MT-90. It's a 75W90 fluid with GL-4 rating that's a perfectly fine replacement any other fluid of the same specification.
2009-11-24 20:49:11
synchromesh..hmm sounds interesting. Maybe I'll try this out next trans oil change instead of the MT90 that's currently in the car.
2009-11-24 21:15:40
bad shaft, or bad diff, or box? which is more likely?
2009-11-24 21:19:47
What exactly are you turning in those videos? It looks like you're reaching inside the CV joint case and turning something?
+ Reply To Thread
  • [Type to search users.]
  • Quick Reply
    Thread Information
    There are currently ? users browsing this thread. (? members & ? guests)

    Back to top