I was wondering if I can use the Castrol TranSynd668 fluid in my 2003 Buick LeSabre ? It has 117,000 mile and has the common hard shift once in a while they say it's a solenoid problem. Ive noticed it happen more when the weather is hot.

Other than loan qualifications it should work fine.
We had a 4000 with 2-3 harsh up and down shift . It absolutely cured it. My guys were stunned .