Trans-Go "No Yo-Yo" kit comes with 1 modded spool valve that stops convertor drainback in P that minimizes this AND potential compromised dipstick O-ring leaks. Negative effect (if any) is that starter fights full convertor on initial cold start, (This was a early design function so initial starts were spinning a lighter, half empty convertor) probably not even felt with today's high torque mini starters or none but the coldest climates. Its under $20 last time I priced one.
