On my 2006 LS430, in the past month or two, it's developed an issue where when I first start and drive it after it's had a chance to cool, it takes longer than usual to shift into 6th. It seems be temperature dependent, with cooler weather taking it longer driving to shift. This may be normal but I don't remember my mom's 2005 doing this and I also don't remember it doing this when I purchased the car in February and drove it in much cooler weather. Shifting between 1-5 is normal and once it does shift into 6th, it's a smooth and normal shift. Transmission does not slip or shift hard.

Based on service records and fluid conditions, it had the original transmission fluid in it until I serviced it last week. A pan drain and fill did not better or worsen the shifting.

Has anyone else experienced this? If so, is it normal or a problem?

 

Has anyone else had this happen with their car?

 

If you only did one pan drain and fill you still have most of the original transmission fluid in there. Three or more are needed to substantially replace the old with new. There is a post on here with the percentages of old v new for different numbers of drain/fill, may be in the "mother thread". What color was the fluid that came out and how many miles on the car?

 

Car had 178,796 at time of service, fluid was brown but free of grit and other debris, felt like good viscosity and lubricity, and didn't smell burned. Transmission doesn't slip or have any difficulty shifting through the first 5 gears, and once it finally goes into 6th that first time, it's business as usual.

I really think it's related to fluid temp/viscosity. I had a Sebring that behaved similarly in cold weather and wouldn't shift past 2nd gear until the trans fluid achieved operating temperature.