Manufacturer lists 75w85 Cold ambient temps make shifting difficult. (Fine after warmed up) Warm temps is fine. Tried RP MaxGear 75w90 and the shifting is impossible until warmed up in cold weather. Warm temps is ok. Now, what I get with the factory stuff is it will go into 1st fine from a stop, and shifting to second or third is very difficult. Doesn't want to, but it has done this from day one. Is this a viscosity problem?