Manual Transmission Fluid Type

I am extremely pissed at the variance of responces I am receiving in regards to the specificed type of fluid to use in 5-speed manual transmission in my 1992 S-10. Since it seems there is no TRUE, DIFFINITIVE answer, I'm posting an opinion poll.


Please, if you feel strongly about a particular fluid TELL ME WHY!!! What is your reference source? Is it a universal answer, or just somethingyou have heard/read? Back up your opinion if you want to be the lucky winner that decides what fluid I will be using in my truck!!


I received the above answers from a variety of sources, including:

1 Jiffylube
1 Hayne's Repair Manual
1 Chilton's Repair Manual
2 ASE mechanics
2 Pepboys
3 Autozones
5 Advance Auto Parts
various posts from this forum (I did a search)

Also, if you have any idea WHY I am receiving so many answers, I would love to know.

Your answer is simple.

They changed the transmission design somewhere around the time that they made your truck.

So it can either be ATF Fliud, or Gear Lube, depending which transmission you have.

Your owners manual should tell you, if you have it.

If you don't have the owners manual you'll have to pull a plug and examine the oil to find out what it has in.
If it's red, and pretty thin it's ATF, or if it's pretty thick, and stinks it's Gear lube.

If it requires gear lube 75/90 gear lube should be fine if you can get it.
And if not 89/90 would work too.

I hope that this helps you out a little.

dexron 3 is mercon (D3 - mercon is what you see it everywhere as) , ive never heard good things about mixing atf and gear oil , gernearally , 80-90 or thicker , is too thick for transmission , and GM dident start using syrnchomesh till late 90's. so, its either 75-90 , or atf , try all data if you know anyone that has it , ill see if i can check it out later

I called a Chevy service center today and was told to use Synchromesh. They said gear lube hasn't been used for a long time now, and that Synchromesh was the specified fluid for my truck. Very few of the non-dealer auto parts stores around here even cary synchromesh, so maybe ATF is listed as a suitable alternative??? Why would ATF be listed in several instances, but the dealership denied that it should be used?

The same reason why Chevy is saying to only buy tires from them.
And the same reason why they tell us to only let them do the maintence on our chevy's

They want all our money, and try every thing that they can to get it.

You did not give them all of the info or they did not ask.
It depends on what engine and trans you have.
From mr. mitch on demand
2.2L 4 cyl -T5 trans takes dexron 3 trans fluid
4.3L - NV3500 trans takes synchromesh trans fluid gm part no 12345345
MT-2500

The same reason why Chevy is saying to only buy tires from them.
And the same reason why they tell us to only let them do the maintence on our chevy's

They want all our money, and try every thing that they can to get it.
sorry, guess its my night to harp on you overboard.... reverse that, Dipshits... i mean autozone wants your business just as bad as the stealership, sooo they will try to sell you what they can when they can, seince the local parts stores are not state or ase certified if YOU listen to them and fu*k something up o well, not their vehical, and they are not liable... the stealership on the other hand, is, you ask them what fluid they reccomend for your tranny (figgure it out, i beleve its a T5) then that is what, and only what you should be putting in there, weather or not you got to your local A to Z parts store or buy OE is up to you, something like that i would go to napa for and be done with it...example... friday we had a 99 fulsize gmc in, this seirra has 2 tranny possibilities, and one has 2 pan options, that was nighmier number one, then the rear end has 4 different ring options and according to napa have 4 different Pure synthetic weights that need to be used, one up to 45 bucks a qrt... the dealership asked what it was, told them the 8.5", asked the moter, and year and knew that it had 4 possibilites, BUT in 99 you could use any synthetic weight in the rear end without fuckup... so, its not just your vehical, its all, it gets frusterating, specally when you have a "cheep" job taking up a lift in a bay at the garauge i work at... btw, i chose syncromesh, dealer only, and i think ive explained why

Your right, autozone, napa and lordco (BC Canada only) Canadian Tire all want all our money.

And they will all do what they can to get it.

The fact is that your owners manual should tell you what type of oil to use, like I said in my first post.

The owners manual will always specify a GM only produce. Shoot I would too if I was a auto manufactor.

But there are also good quality aftermarket oils that are a good alternative to GM's product line.

It's entirely the car owners choice what brand of oil he gets.

Of course brand selection all gets thrown out the window if you ever get stranded in a small town where you only have 1 or 2 choices. You'd be a moron to wait for a few days for your favorite brand of oil.