Franchute13 wrote:Hi.
Today we did the test. We used the 2 cars.
Same route, same speeds (90km / h - 120km / h). My car showed 12 C degrees warmer on the box oil. (94C vs 106C).
I must have the heat exchanger faulty.
My current Xantia V6 also peaks at about 94 degrees under high speed and acceleration, so I think your friends cars gearbox oil temperature is normal. 106 degrees under the same driving conditions is not normal and is about the same temperatures I was seeing on my old Xantia V6 with the overheating gearbox which was burning the oil all the time and eventually failed.
So your gearbox is definitely overheating, it just remains to confirm whether it is due to a blocked heat exchanger as we believe or if it is a more serious problem inside the gearbox. If it is the heat exchanger and you can get it properly unblocked or replaced you might get away with doing that and doing some oil changes to dilute any burnt oil, hopefully there is no permanent damage to the clutches in the box.
You would also need to find why the heat exchanger was blocked - it would only block if the coolant was poorly maintained or someone used some stop leak in the coolant - on the Xantia V6 it's very common for the coolant expansion chamber to split around the seam and leak under pressure, so I suspect a lot of people put stop leak formulas into the coolant that then block the heat exchanger and cause the gearbox to overheat.
If the problem is not the heat exchanger and is something in the gearbox then there is probably nothing you can do about it as it won't be economic to rebuild.