Hi want to ask what oil should I use on late mpi automatic mini. Its my first automatic so I'm not sure TIA

Early Matics here in Oz were recommended to use 10W/30 to 20W/50.
A Rover MPI is basically the same box with some improvements.
Here in sunny Oz I would use cheapo 15W/40 or 20W/50 mineral oil, with no friction modifiers.
I used to run my Matic (when it was one) on Valvoline XLD 20W/50.
If you look them up for UK use, they probably specify the thinner grades due to lower temps there.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.