@Ardent
I found a European website (https://www.toyota-tech.eu/) but I don't know if it's the right one/reliable.

The Toyota Tech website is the right one.  You can pay for access hourly and all of their workshop manuals are available to download for personal use.  Navigate to the MR2 section and download like crazy until you have the full set.  It took a couple of hours when I did it a while ago.

Happy hunting

In my opinion, anyone who has set the oil level of a 6-speed gearbox like mine using the hole with the 10 mm Allen bolt is driving with 0.4 - 0.45 litres of oil less than required.

Quote from: Beachbum957 on January 10, 2026, 11:42The fill plugs for the 5 speed and 6 speed are in the same location.

Transmission Fill Plug

You're wrong, unless you know more than Mr. "T," and in that case, I raise my hands and apologize.

The fill plugs for the 5 speed and 6 speed are in the same location.  The only difference seems to be the 5 speed used an external hex, and the 6 speed has an internal 10 mm hex.  When we change fluid in a 6 speed with LSD, it took just over 2 US quart, but we didn't measure exactly, just filled until the oil dripped out the fill plug. Here is a link to a picture, probably of a 5 speed.

Transmission Fill Plug

I'm not surprised no receipt for a gear oil change. I think they were a filled for life type thing.

Don't think Mr T, (toyota) were expecting these to be running around in 20 years time. 

Quote from: Ardent on January  9, 2026, 20:01I've been here a while and the references to repair manuals all seem to be from one source. I'm not sure if the original was updated or not to reflect any changes.

That said, you can go on the toyota site and pay a fee to access/download what you need.

With a bit luck you can find the link in here somewhere or hopefully someone will pop along with it.

Thanks Ardent, following your suggestions I went to the European website, created an account, paid to consult the repair manual, and now I can confirm that my intuition was correct and for my 6-speed transmission c65 or c66, the fill and level hole is the one on the right with the bolt that unscrews with a 17mm spanner.
I think someone here will need to add a bit of oil.

Since the hole and the 17 mm bolt  is not shown anywhere in the repair manual for the 5-speed gearbox model, I am inclined to believe that this is the right hole for filling and adjusting the level in my 6-speed gearbox.
I also checked the service receipts for all the services carried out on the car, all at Toyota dealerships, and it seems that no one has touched the gearbox oil. I am reasonably confident that the oil level I found in the car was the same as when it left the Toyota factory in 2003.

@Ardent
I found a European website (https://www.toyota-tech.eu/) but I don't know if it's the right one/reliable.

@Joesson
I do not intend to fill the gearbox through the hole provided for the speedometer.
I am sure that the photo I posted is taken from the workshop manual for the car with a 5-speed gearbox.

@alexcap
From what I remember that illustration in post #5  is nothing like the gearbox on my 2002 MR2 with a 5 speed box.
Some members will recall the discussions about the port at the top of the gear box, blanked off, used on other cars to connect the speedo drive. That was sometimes suggested, incorrectly as an alternative filler hole.
From my recollection on my 5 speed box the drain plug is obvious, the lowest point of access.
For the filler hole there was a choice of two " openings"  on the front vertical face of the box, which one became obvious as the other went nowhere.

Quick search gives
https://techinfo.toyota.com/techInfoPortal/appmanager/t3/ti?_nfpb=true&_pageLabel=ti_home_page&SMENC=ISO-8859-1&SMLOCALE=US-EN&SMAUTHREASON=0&SMAGENTNAME=%24SM%24mT%252bGLraBu9CwUVnZg4mEDzB2kysT90hgbwsWgdZzNOc%253d&TARGET=%24SM%24https%3A%2F%2Ftechinfo.toyota.com%2F

A more eu based may exist

I've been here a while and the references to repair manuals all seem to be from one source. I'm not sure if the original was updated or not to reflect any changes.

That said, you can go on the toyota site and pay a fee to access/download what you need.

With a bit luck you can find the link in here somewhere or hopefully someone will pop along with it.