I have a 2003 GMC Envoy with the 4.2L inline 6 that I got about three months ago. It has 109k miles on it. I noticed that it was shifting hard when going from 1st to 2nd gear when the vehicle was cold. It seemed to be shifting at a normal point as far as RPM, just shifting hard. Last week I changed out the fluid (the old fluid wasn't that bad) to Castrol synthetic. It helped some, but this cold shifting is still an issue.
Before doing the fluid exchange I tried Lubegard red. It didn't do anything. Now, I'm not sure whether to leave things alone, or try LG red again, or Lucas Transmission Fix. The Lucas is thick, but I don't want to screw something up. At worst the LG will just not do anything.
Another note: today it was 32 degrees (F) outside. I let the vehicle warm up about 30 seconds as I normally do, and it seemed to shift fine once I started to drive even though the vehicle wasn't warm yet. So I don't know if maybe the synthetic fluid is having more of an effect due to the cold, or if it is just taking it a while to start helping more?
Just not sure what to do, re: LG red, Lucas, or leave it be?
Before doing the fluid exchange I tried Lubegard red. It didn't do anything. Now, I'm not sure whether to leave things alone, or try LG red again, or Lucas Transmission Fix. The Lucas is thick, but I don't want to screw something up. At worst the LG will just not do anything.
Another note: today it was 32 degrees (F) outside. I let the vehicle warm up about 30 seconds as I normally do, and it seemed to shift fine once I started to drive even though the vehicle wasn't warm yet. So I don't know if maybe the synthetic fluid is having more of an effect due to the cold, or if it is just taking it a while to start helping more?
Just not sure what to do, re: LG red, Lucas, or leave it be?