What is the real change interval of the manual transmission fluid?

[Totally 80s]

I've seen owners say they change the transmission fluid every year, every two years, etc. I'm going on 5 years with my fluid with no problems. What is the REAL change interval for a car that gets maybe 2000-3000 miles tops a year?

[Michael]

Damn, I just read one of Dave's posts about this. I remember it was way short of the factory intervals of 30k. I think he recommended every other oil change or once a year...whichever came first. That's just my memory though so don'tput a lot of stock in that.

[Totally 80s]

Damn, I just read one of Dave's posts about this. I remember it was way short of the factory intervals of 30k. I think he recommended every other oil change or once a year...whichever came first. That's just my memory though so don'tput a lot of stock in that.

I've seen stuff like that written but that seems like crazy over kill for manual transmission fluid. What is happening inside the transmission that is making gear oil go bad in a year?

[Josh]

Yeah that seems ridiculous. Especially for guys running $20 per liter fluid.

[john 05141]

Every other year for me.
I drive about 2000 to 3000 miles per year.
I used to have to push hard to get her into first gear when cold; Since I change the oil every other year that problem is gone.
The oil looses quality every time it heats up and this transmission can get pretty hot.
I think it is cheaper to maintain it well.

Jan

[Michael]

Ooops...I didnt read close enough. I was referring to automatics.

And I am thinking it's overkill too. I did a 30k service minus the valve adjustment when I first got my car (which only had 1,700 miles on the new engine..but almost 3 years elapsed time) I just recently did another transmission service at 15k miles and approx 3 years elapsed time. For me it's a bit overkill to do it often but like I said in my first post, I'm not sure I'm quoting Dave 100% on that.

Edit. Found his quote. Remember he is referring to automatics here:

My personal belief, is that the ATF should he changed with every other engine oil change, and the diff changed every 30K miles or 10 years. For most DeLorean owners that means the ATF every 2 years and the rear oil every 10.*

FWIW factory recommends all fluids at 30K.

[David T]

Ooops...I didnt read close enough. I was referring to automatics.

And I am thinking it's overkill too. I did a 30k service minus the valve adjustment when I first got my car (which only had 1,700 miles on the new engine..but almost 3 years elapsed time) I just recently did another transmission service at 15k miles and approx 3 years elapsed time. For me it's a bit overkill to do it often but like I said in my first post, I'm not sure I'm quoting Dave 100% on that.

Edit. Found his quote. Remember he is referring to automatics here:

Frequent oil changes in the manual transmission IS overkill. The frequency is usually driven by the # of miles accumulated. The oil doesn't wear out so much as it accumulates particle load from wear, principally from the syncros and the crown wheel. It is non-ferrous so it doesn't pose any danger to the ferrous parts. The problem is if you do it on the basis of mileage and you drive 1K a year you don't have to change it for 30 years! So now we should be changing on the basis of time. Every 10 years seems about right but you must keep good records for that length of time so you know the last time it has been changed.

[krs09]

I know Ive read this somewhere but whats the general concesus for manual trans fluid? Brand, weight, any info would be great. Thanks guys and gals.

[Nicholas R]

I use 80w-90 gearbox oil. Nothing special.

[Jason]

In case it's useful, here is what came out of my transmission after about a year and a half and 8000 miles. Next to it is some unused oil from one of the bottles I used to fill the transmission originally.

26760

I don't change the transmission oil this often. I was attempting to top it off because I have a leak in the drivers side flange seal (even though I replaced the seal a year and a half ago) that I haven't had time to fix yet, and that's what came out of the fill hole when I opened it. I guess I somehow managed to overfill the transmission bit when I first filled it (not sure how) and overestimated the amount that's been leaking.

[David T]

In case it's useful, here is what came out of my transmission after about a year and a half and 8000 miles. Next to it is some unused oil from one of the bottles I used to fill the transmission originally.

26760

I don't change the transmission oil this often. I was attempting to top it off because I have a leak in the drivers side flange seal (even though I replaced the seal a year and a half ago) that I haven't had time to fix yet, and that's what came out of the fill hole when I opened it. I guess I somehow managed to overfill the transmission bit when I first filled it (not sure how) and overestimated the amount that's been leaking.


The car must be level to check it properly. If the front is higher or lower than the rear it can make you think the transaxle is under or overfilled. A small leak appears to be larger than it really is, a little bit goes a long way. For most British cars the saying is, when it stops leaking it is time to check it! Color is not all that meaningful when checking gearcases. Smell and feeling it between your fingers matters more.

[GS450-Junkie]

So the procedure on a manual transmission fluid change is to level the car, open the bottom drain plug and drain. Reinstall drain plug, and open the side plug which is up on the side of the transmission...not sure how the bottle is supposed to fit up there, but add fluid thru that plug until it reaches the bottom of the hole. Put some Teflon tape on the threads when reinstalling, and use 80w90 oil...should take about 2 quarts..And that's basically it. Nothing else to check or change?

Has anyone on here used Lucas oil in the manual transmission? That would be 1 quart Lucas with 1 quart generic?

[sdg3205]

Dont drain the transaxle until you know for certain the fill plug will come out. Once you do, drain away!

You can buy "oil transfer pumps" for this type of thing. I have a few length of clear vinyl hose from home depot that fits over the oil bottle nipple and into the transaxle housing. Cost a few cents and is much less easier to drain, clean and store. Also use it for differentials and transfer cases. Buy a few feet and you can use it to beed your cooling system, brakes etc.

[Gregadeth]

Where exactly is the fill plug located on the transmission? And is it a special kind of socket? Thanks

[sdg3205]

It's a female square drive. I forget the size but I have a socket from snap on

[DMC-81]

Where exactly is the fill plug located on the transmission? And is it a special kind of socket? Thanks

Hi Greg,

The fill plug is located on the passenger side, between the drive axle and the front of the gearbox. The tool is the same as the drain plug. I used CTA 2048. It's a 10mm square socket.

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