When I built my SP with POSTON KIT some 8 years back, the instructions said type "F", which has been working just fine.
I started this thread back in '06 because I wanted to get that Cat 30wt Oil out of there. The car just would not move for about a minute or so after starting the car cold, then it would be fine the rest of the day. I ended up going to Mobil 1 synthetic transmission fluid. That worked great for a couple of trips to the track and then the switch pitch converter self destructed. When I drained the converter lots of parts came out with the fluid. This summer I went thru the trans and converted it back to a fixed pitch converter. I ordered one of Jim Weiss's 4500 stall 9.5" converters and I'm using a name brand Dexron fluid that he recommended. I have yet to go to the track with it this year but on the street it feels amazing. I can cruise around with the kids and it's not slipping like I expected a 4500 stall converter to do but when you nail it it pulls like never before. The car ran 11.18 on the last pass before the converter broke on the drive home, with the way this car pulls now with this converter I think it may have the high 10 I've been looking for. No more Cat oil or switch pitches for this car. My dad ran a 4000 high stall s/p in his '64 Riviera for many years using a 100 shot of nitrous right off the line and never had a problem with his and he uses regular Dexron fluid. Ken
