Manual transmission gear lube

I had my 2015,5spd gear lube changed at 30,000.mi. Now it seems to shift hard when cold. I did not notice this with the factory lube in there. Dealer did not do it,but my mechanic did. Question is, did he put the wrong lube in and will it do harm. Thanks

 

And how would we know that?

If someone around here tells you they can give gear lube specs by the feel of a shifter, don't buy anything they have for sale.

Wouldn't it be easier to ask the mechanic what he used? And see how it matches, spec wise, to what your owners manual calls for (likely 75w90 GL4 or GL5)

 

It has been super cold lately , it just feels stiff until it gets warm inside the gear box.

 

My 5spd has done this since it was new.. ive had it flushed a time or two at the dealer and it is still behaving the same. Seems to be normal for mine. typically it only happens on cold mornings and only lasts until the trans warms up a little. If yours wasnt always this way, i too would be questioning it. subbed for outcome

 

I've been reading up on transmission lubes, in a transmission with brass synchro's, it's best to use a GL-4 lube NOT GL-5 lube. The additives in GL-5 will eat away at the brass synchro's and cause hard shifting.

 

AS suggested, find out what he used. If it was a GL-5 or a GL-4/5, then he will need to drain and refill. If you are serious about your truck, then buy Redline MT-90, or if you are driving in very cold weather, Redline MTL might be a better choice. I've tried a number of different lubes and nothing comes close to Redline in this truck

GL-5 will eventually eat the brass synchros as stated. The shifting problem you are having is because synchros need a balanced amount of friction to actually sychronize the gears during a shift. If the lube is too slick, it will prevent the gears from synchronizing during the shift and you either grind gears or get hung up trying to make a quick shift.

 

Changed mine a while back with Redline MT-90 GL-4 and have had no issues what so ever.

 

I changed mine for the first time about 2 years ago with ~50k miles on mine. I used the MT90 gl-4 and I swear I noticed my shifting to be a little 'notchier' as the truck was warming up. I was a little disappointed at first, but since I double and triple checked that I used the correct fluid, I chose not to worry about it. 2 years and 20k+ miles later, I don't notice it and have had no issues.

 

In my truck, the switch to MT-90 was not an instant miracle either. It took a little while for the shifting to clean up, but it did. Now my shifting is very good.

 

I swapped in a low mile 6spd trans during the summer and when I did I used rl mt-90 and I have to say the syncros feel real gritty maybe grind maybe notchy is write word as was used above. Thinking of draining and trying something else? It makes me nervous because my syncros started going at 115k on my other gearbox.

 

Back in my 2000 Tacoma when it was cold outside it did not like to go into 2nd gear, I swapped some Amsoil in the trans and that problem magnified, I had to go from 1st to 3rd until the truck warmed up, other than that it shifted better.

 

Redline MT90 for the win!!

 

Amsoil Severe Gear 75W-90.

 

Is that a GL-5 lube? I could not find that info on the link, but there was a mention of "an iron sulfide barrier" formed on the gears. As I recall the GL-5 additive that corrodes synchros is a sulfur compound.

 

"Recommended for use in differentials, manual transmissions and other gear applications requiring any of the following specifications: API GL-5, MT-1, MIL-PRF-2105E, Dana SHAES 234 (Formerly Eaton PS-037), Mack GO-J, or the differential (hypoid) gear oil specifications from all domestic and foreign manufacturers such as GM, Ford and Daimler Chrysler. Can also be used in axles where an API GL-4 lubricant is recommended."

 

Guess I'd best get my glasses checked. At any rate, those who are concerned about GL-5 in their transmissions (me included) might want to use something else.

 

Talked to my mechanic today,said he put gl5 in the tranny,same as the transfer case. He said it was a expensive synthetic gear lube.Said that it my have a little to much oil in there causing a hard shift when cold. He also said to keep an eye on it,if it continues to shift hard we will try something else. I'm more confused now.

 

Your boxes will be fine with GL-5 but the brass syncros in our MT's DO NOT LIKE GL-5.

You should ask him why he didn't put manufacturer recommended GL-4 in, then tell him to drain and fill your Trans with GL-4.

I'd recommend MT-90 for MANY reasons.

 

There is no confusion.

Get another mechanic. I would not let him check my tire pressure. Drain the fluid and fill it yourself. Chalk it up to experience.
#1..GL-5 in the transmission and Tcase is bad news
#2..how can you overfill a transmission with a side fill hole?
#3 ..overfilling causes the box to puke oil, not hard shift. It can also blow seals.
#4...what the hell are you supposed to "keep an eye on"???

You need an oil that is specifically formulated for a synchronized gear box. These Toyota transmissions are the most oil sensitive boxes I have ever seen. Manual transmission / Tcase oil is not interchangeable with other applications. Redline makes a great oil for this purpose.

What you do is your choice.

 

250k miles Redline MT-90 all the way never an issue with shifting or other wise...