Accidentally added mercon 5 to dexron 3
Asked by Gurl Oct 26, 2018 at 08:32 PM about the 2002 Pontiac Montana 1SE Extended
Question type: Maintenance & Repair
I accidentally added Mercon V transmission fluid
to my Pontiac Montana minivan which is GM calls
for Dexron 3 or Dexron 6 and now it's slipping really
bad and so I would like to know if I change the fluid
if it's going to be okay
5 Answers
Change the fluid and drain the converter. You may want to consider a flush.
JaredatAllAboutCarsd... answered 6 years ago
If your transmission is slipping badly and the fluid level is correct, you will only be wasting your time and money changing the fluid. Automatic transmissions almost never recover from damage without rebuilding them.
Since the alternative is several grand for a rebuild it is probably worth a try.
If you just added a quart or less of Mercon V to a Dexron transmission, I would doubt that it caused this issue. Changing the fluid will likely not do anything and a rebuilt may be in your future.
Drain and change the fluid. I doubt if any damage has been done if it has not been over a few days and less that 100 miles. Be sure to drain completely including the torque converter.
