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Cavalier manual transmission fluid

I have a 2001 Cavalier 5-speed manual 2.2. I have owned it for every day and every mile (204K) since I bought it new in April of 2001. I have had many mechanical disasters and problems mostly starting a couple of years ago - and a lot of them I have worked on or fixed and/or replaced the part myself.

The transmission fluid in this car has never been changed, looked-at, drained, added, etc…because I was told that it didn’t need it. The manual says the same thing. For as long as I’ve had this car, it has had a intermittent rattle noise that I figured was just the “Getrag rattle” - so I didn’t pay much attention to it. But over the past year - especially the last 6 months - this rattle has just gotten totally insane and out of control. It is now a constant loud rattle whenever the car is in gear - especially starting out in 1st or 2nd. I mentioned this to someone and they asked when the last time the fluid was changed and said that would fix the problem - and couldn’t believe that the fluid had never been changed after 15 years and 200K miles.

This model has no dipstick. There is a big red vent cap and I think I found a HEX plug close to it, but before I go out and buy the wrong size hex key - can someone tell me what size these are and if they are even what I am looking for to fill/check/drain it? So frustrated. Also - since I can’t find DEXRON 3 anywhere am I supposed to use this DEX/Mercon stuff ? Any help, ideas, suggestions, info would be great. Thanks.

DEXRON 3 is for automatic transmissions, usually. What does your manual say for fluid? Whatever is says, use only that.

But I doubt a fluid change will fix anything at this stage. But I’m not an expert…

“DEXRON 3 is for automatic transmissions, usually”

Usually, yes, but the manual transmission for my old Chevy Citation used Dexron for its lubrication, so it is entirely possible that this Chevy Cavalier also uses Dexron. As long as the OP is sure that he is looking at the fluid spec for the manual trans (and not an automatic), then he should buy the latest incarnation of Dexron fluid.

However, as BillRussell noted, it may be too late for a fluid change to make much of a difference with a transmission that has already exceeded its design life.

That era GM product used Dexron ATF for many of their manual transmissions.

Let me clarify.

1.What is the current ATF to use for a car that is supposed to take Dexron III since you cannot buy Dexron III anymore?

  1. What size/type tool is required to get the fill, check and drain plugs off the Getrag F23/M86?


Dexron 3 has been replaced by Dexron 6 which is synthetic and is far superior. They are compatible.

See my follow-up posts below.

Op’s description could be a worn countershaft bearing. Just a guess without an inspection and test drive. Of course if the fluid level and condition has not been checked in 15 years/200,000+ miles there could be multiple problems. M/Ts should have that done at least every other oil/filter change.

Do not use Dexron VI in the transmission!


As to the size hex tool, just look at it !!!

“What is the current ATF to use” ?? but this is not an AT, this is manual.


Sorry, but I have to agree with the others

There are many cars out there that use atf for manual transmissions

And some use engine oil.


The transmission fluid did not cause your problem and changing it will not fix it. It did come with Dexron III and it never needs to be changed. Unlike an automatic transmission, the ATF in the manual never gets hot enough to break down, not even close. It is sealed so other than normal wear of the gears and syncros, there is no contamination. Once the syncros and gear wear down enough to affect the ATF, the transmission is worn out.

I put 275k on the manual in my Saturn 5 speed and it was always silky smooth. I only occasionally checked the level by lifting that red cap and pulling out the attached dipstick. It never got low and was always bright red.

I feel @keith may have a point

While changing the fluid can’t hurt, it’s quite possible/probable that it also won’t fix any problems

However, I disagree with him on the idea that fluid in a manual transmission never needs to be changed

Without even going into any technical discussions, I know for a fact that many owner manuals DO have a service interval for the fluid in the manual transmission

You’re more likely to get away with never servicing it, unlike with an auto trans, but that doesn’t really mean it’s the right thing to do

Transmissions are not sealed.

They have vent usually in the form of a hose.

Without it, the gears/oil would heat up to a point where the pressure would build and blow the seals out of the transmission.


I stand corrected about the vent, but the gears and oil in a manual transmission do not get all that hot. It is not under pressure like in an AT.

If it is an allen stud you might want to use a maybe 8mm allen socket

db4690, I agree. I was just commenting on the OP’s statement.


Seems like @Tester is right on not using Dexron VI in a manual transmission. I also see that Dexron VI may not necessarily always be synthetic. My apology for the bum steer.

OK, a little more research shows that the reason Dexron VI is not recommended for those earlier manual transmissions is that it was introduced after GM stopped using ATF in more recent manual transmissions so it was never tested or approved for that application.

It’s probably best not to use it in manual transmissions.