Don't trust the 1.55 L figure. Check the level. One owner drained far more than 2 litres from his NA gearbox, refilled it with 1.55 L assuming the previous owner had overfilled it, and a week later the gearbox destroyed itself (the small nylon parts on the ends of the selector forks melted off). He refilled it from the level plug, as the manual says, and the box took all of the 2 litres he had bought and still wasn't nearly full, so he thinks 1.55 L is "seriously pessimistic". He admits the box was already shifting badly, so the fault may have been there first. His advice is that if you can get the level plug out at all, do it. The other guide (F23 gearbox removal and clutch replacement) also says some F23s need more than 1.5 L and to use the level plug to get it right.
This 2005 guide is for an NA. The author wasn't sure whether the same applies to a Turbo ("VXT"), and a later question asking what oil a VXT should use got no answer. His car had done 34,000 miles, and he says that if you track the car you should do this more often than the 60,000 mile service interval. All the photos have been lost from the forum, so this guide is his written steps with later comments.
Help wanted
The thread has no photos, no torque values for the plugs, and no oil specification. It doesn't confirm the right amount of oil, and it doesn't say whether the Turbo is the same. If you have done this, tell us your car's year and engine, how much oil it took to reach the level plug, and which oil you used.Steps
- Warm the gearbox with a good drive of about 30 minutes. Then find the fill plug (8 mm Allen socket), below the expansion bottle. Fit an extension and loosen it, but don't remove it yet. It is very tight and may need a big extension with a breaker bar. The author says it feels as though you will spin the car before the plug releases.
- Remove the undertray. You need to remove the rear tray as well if you want to reach the level plug. The author didn't use the level plug because the engine mount bracket blocked access, and he says it is only really critical if you can't measure the oil going in.
- Find the drain plug on the left-hand side of the gearbox, below the left driveshaft.
- Undo the drain plug. Then remove the loosened fill plug to help it drain. His photo showed an arrow to the level plug with the rear tray off, and the engine mount bracket in the way.
- Let the oil drain for about 15 to 20 minutes.
- Refit the drain plug, and fill the box through the fill plug opening. He used a little clear hose, which is easier to measure with and stops a mess.
- Refit the fill plug, and check for leaks from the drain plug (and the level plug if you used it). Refit the undertray.
Notes from the thread
- Slight overfill and the breather: the author slightly overfilled to 1.6 L, and did the gearbox breather modification so any excess could blow out safely. He took a photo of where he fixed the breather pipe, but it is lost.
- Additive: he also added some Slick 50 gearbox treatment, and said the box was much nicer and slicker from cold. He says some people don't agree with these additives, and nobody else in the thread commented on it.
- Stuck plugs: the plugs are an absolute pain to remove. Another owner agrees with the author.
- Quaife differential: a Quaife ATB diff uses the normal gearbox oil, and a proper plate-type diff needs a special oil. One Quaife owner confirmed his needed the standard oil.
- Oil choice: the red GM gearbox oil was thought cheaper than the Castrol oil from Halfords. This is a recollection of 2007 prices.
- Spilled oil (2009): one owner asked, after losing gearbox oil on track, where and how to top it up, and whether another guide with pictures was available. The thread gives no answer. The fill plug is the one below the expansion bottle, as above.