Added MT90 Fluid, Now 3rd Gear Grinds

yeah it seems like there are a lot of threads about it where people sing it's praises like it brought their transmission back to life, but I didn't really notice any difference at all. Then again I think my trans is in good health so I suppose there wasn't much to expect except a normal feel.

 

I switched to mt90 a couple months ago. Before the switch I could barely get the dang thing into first gear especially when cold. After the switch to mt90 it shifts very nice & smooth now but it would sometimes grind on the 1 to 2 shift but never on the 3 to 2. It wasn't consistent either and was driving me nuts. I was wishing I would've bought the mtl fluid but then after driving it for about 500 miles that issue has gone away and it shifts very smooth into every gear. I have a 2.7 with the 5 speed.

 

That's helpful. Maybe I'll give it a few weeks.

 

Yeah, I'd give it a couple of weeks.

I put MT90 in mine and it cured an intermittent grind into 4th gear that I was having.

Never had this happen on the Tacoma, but I have had grinding gears on other vehicles just after a gear oil change, then it worked itself out. I don't understand why, but it was a consistent thing on one of my trucks.

 

I'll put another feather in the hat and say that I've used Motorcraft full synthetic manual trans fluid in my 6 speed and it's worked great. OEM fluid previously was a bit knotchy going into 3rd when cold, switched to the Motorcraft fluid and it's very smooth at all times... cold or hot. Shit is expensive though for Ford fluid lol.

 

I used MT90 the first time I changed my transmission fluid because a lot of people rave about it on here. I had the same issues of notchy shifts and clashing gears. I've been using Red Line 75w90NS since and it's a night and day difference.

@EatSleepTacos

 

I was reading an old post on here that Ford part number XT-M5-QS was a very good transmission fluid.
https://www.fcsdchemicalsandlubrica...ransmission+Fluid&category=Transmission Fluid

 

That's the Motorcraft stuff I was mentioning. It's worked well for me and I do recommend when I can.

 

It should be noted that Redline now has a whole suite of manual transmission oils. They used to just have MT-90 and MTL. It might be worthwhile to try some different formulations. Redline still recommends MT-90, but I'm going to give them a call and have a chat.

 

You might try making sure your not over full. I overfilled mine with MT90 and 3rd was notchy. I did it on the street which is a hill so I had about 1/4 qt extra in there. Drained the extra off, shifted like a dream. Also I can’t remember but I think the FSM doesn’t call for fluid dripping out when full I think it was like a 1/4 below the full hole or something like that. You will have to check.

 

The best way to check oil level is with a piece of wire bent 90 degrees and inserted into the fill hole as a dip stick.I keep a piece of white electrical wire in my truck tool box for that. The end I hold is bent into a ring so no possibility of dropping it inside.

 

Funny, I just started a thread about

$34 XT-M5-QS Full Synthetic Manual Transmission Fluid - 1 Quart , black

XT-M5-QS yesterday because I hadn't seem much about that oil on TW... I switched out Redline MT-90 for XT-M5-QS and so far thinks it's smoother into 2nd and 3rd. (Only had it in a couple days). I bought it on RockAuto and it was no more expensive than any of the other syn 75w90 GL4 oils; ~$15/qt.

 

How about API GL-4 or GL-5? synthetic? Only time mine grinds is when I screw up not the trans.

 

I also tried the Ford "honey" and at first liked its shifting qualities. I got nervous about using it again when I drained the stuff and it came out almost black. So, IDK.

 

Good info. I had to look up the 75w90NS as I hadn't even heard about it before.

I think this will be my next step if this MT90 doesn't work itself out.

Let us know what you find out!

That's interesting. I didn't know overfilling was possible. I actually jacked up the driver side of the truck slightly to make sure I could get plenty in there, so if overfilling is possible, I did it. I might try parking it on level ground and taking off the fill plug to drain out any excess. The third gear grinding has actually gotten much better, but still happens occasionally when it's cold and i'm not being careful.

 

People are spending lots of money on the

$34 XTM5QS Ford Genuine Ford Fluid XT-M5-QS Full Synthetic Manual Transmission Fluid - 1 Quart , black

XTM5QS online... It's 15 bucks on rock auto... Buy it there rather than Amazon,etc.

 

Update:

I drained just over half a quart of the MT-90, and added some MTL (75w-80) to fill it back up. The shifting is definitely improved, but will still occasionally grind going into third for the first few shifts after a cold start. I think I'm going to give the

$34 Ford XT-M5-QS Full Synthetic Manual Transmission Fluid - 1 Quart , black

Ford XT-M5-QS a try next.

Is a grind in 3rd gear a sign of transmission failure to come? Or could it have this issue for another 100k miles without failing?

 

Do not expect the 6-speed to shift well when cold. Its just not its nature.

If you look around you may find a post or two stating that I have had the RA60F apart and have completely rebuilt a couple now.

Unfortunately, the 05 and 06 have seen the most problems and the 6-speed has had a multitude of internal part revisions. On yours I might suspect one of the shift forks that was originally cast aluminum, and cracking/breaking (now replaced with steel or cast iron), or the shift keys in the 2-3 slider and hub and sometimes 5th gear as well.

The springs on the shift keys mentioned like to pop out of the key and get lodged sideways between the hub and slider or even break causing the hard shift. Occasionally 3rd will jam and shifting ends altogether.

You can try the Ford "honey" noted and if you do not find a significant improvement the matter lies inside.

 

My 05 has 185,000 miles on it, and it grinds a little going into third. Been that way since I bought it over a year ago with 168k on it. I wouldn’t worry too much.

 

That's reassuring. Thanks.