Hi everybody, I'm from Chile and I've an Cady Catera (Opel Omega MV6 down here).
I'm having problems with the transmission (the 4L30E).
When I drive at about 60km/h (38mph) the transmission slips (it goes to neutrum I think) for a few seconds and then I feel a big punch. Then lights the transmission light and it goes to "manual mode". But when I shut down the engine and start it again, the problem fades.
When I drive above that speed the problem goes away.
There is also a problem in low speed (below 50km/h/31mph). When I realese the throtle I can feel a litle punch (not as big as the "60km/h punch").
All this hapen with a warm engine and transmission. When they are cold, all works perfectly.
It could be these things: Torque converter, valve body on the transmission, or its getting improper lubercation (aka valve body then). BUT being that its all electronically controlled, who knows what the computer is thinking. It'd be best to have someone OPEL Certified take a look at the car and give you a proper diagnosis from not only the transmission but from a quick drive to see what they think.
Thanks.
What about the transmission oil. Can be that. I think it's the original oil and the car has 120000km(75000 miles). But in OPEL they say me that is a litle complicated changing the oil to this transmission. They recomend not to change it.
Yep that would be the case, you have to know how to take off the valve body and other parts so it can all drain out... not only that but if you wanted to change the Torque converters' fluid then you have to dissconnect it from the engine (The transmission) and then take out the torque converter and disassemble it.
There should be a dipstick in the engine compartment; although Im not quite sure i saw one... there should be. Its as simple as checking engine oil, but you have to have the engine running when you do it.
I found how to check oil level in this transmissions.
With the engine running and AC on (for increased idle speed). Apply Parking brake and move the selector lever trough all positions.
With the engine running and the lever in Park remove the filler plug. If a small stream of oil runs out, the level is OK.
I found it a little complicated, but is the only way.
Re: Catera transmission problem 
by the way
