changed my box oil yesterday on a 6 speed but may have done it wrong?the problem i have got is i only put 3.5 litres back in and its registering well over full mark on dipstick which isn,t good because it should take 4.1 litres! when i drained out the old oil i only took the drain plug out of the gear box sump thinking its the lowest point on the box so why bother taking out the big drai plug under the front diff,is it possible that there was over a litre of oil still in the front diff casing that didn,t make it back to the lower sump? looking from under the box the diff casing looks to be on the same level as the main box but is there some sort of wall where the two bolt together that could have been holding some oil? the oil that was in the box was silkolene now its syntrax will the two mix together or not ?any advice would be appreciated.
thanks dean.

 

you need to do both drain plugs

 

Anyone got a pic of both drain plugs as I've only ever done one, the one towards the front (engine side) at the bottom of the box which is easy to access with the plastic tray still in place...where's this other drain plug? Not noticed it taking less than the required amount using that plug (which is also the magnet).

 

It's hidden by the plastic cover under the gearbox. Two clips at the front (which also clamp the rear of the big engine tray) and bolts at the rear. With this off, you'll see the small sump at the bottom of the gearbox. the drain plug is at the front of this.
JohnD

 

Cheers for that Johnd...learn something new every day - I never even questioned it before as I thought the right amount of oil went in the box last time.

 

took oil out of box again and threw away incase of problems with fully syn a semi syn not mixing together ( waste of £44) took both drain plugs out this time raised rear of car , raised front of car to make sure there was no oil at either end of box, left to drip dry for about 2 hrs. put plugs back in and filled with syntrax again and its still only taken 3.6 ltrs to the full mark on dipstick.why is this when it should take 4.1 ltrs to fill.but on the plus side the 5th gear crunch seems to have gone, i,ll let you know if it comes back also all gear changes feel smoother with syntrax in compared to silkolene syn 5.

 

Excellent news (except amount put in I guess), makes me happy thinking I've got Castrol in the post on way to me although it will prob take a month to get there now with the Royal Snail the way it is
I'll report back on what my box takes when I do the change...but wont be till early next year.

 

Make absolutely sure the car is dead level when you check the g'box oil, it's quite sensitive to this.
JohnD

 

Here's notes from my mapper (Bob Rawle) ref gearbox oil changing...
"Yup two plugs, one in the small sump and is at a horizontal angle, the other is recessed just forward in the bottom of the diff bulge, makes a big difference, also, with both open drain with the car flat for say 1 hour, then jack up the rear under the diff to get the caught stuff out, you will be surprised." - sounds perfect for getting all you can out of the box!

 

some how imust have had some oil still left in box will the silkolene syn 5 that was left in there (about 400ml possibly) mix alright with the syntrax?

 

Erm, one for the oil ex...perts but I had GL4 in my ford box changed for silkolene (def not 100% change) and box been lovely since...30 K miles

 

i spoke to a oil expert down at the pod today he said shouldn,t be a problem. gear changes are still nice and smooth with no crunching.fingers crossed the syntrax may have solved the problem.

 

I sure hope it does the same for my box as she's low miles...would save a heap load on rebuild costs....fingers,legas adn amrss crossed.