Well... U1P stay 1 (or 2) steps under RL, if it's ok good if it's cheaper too.Recently replaced the redline MT-90 with Ultra1plus 75w90 gl4 in my NC3 Miata, shifting is very smooth, still within first 1000 miles.
His cousins/brothers:this stuff right here is excellent
Ford MOTORCRAFT® Full Synthetic Manual Transmission Fluid XT-M5-QS (UNICORN TEARS)
- Ford BO 75w90
- Castrol BOT 130M
- Castrol BOT 328
- Castrol Multivehicle 75w90