Penrite HPR30 has the inferior base, I found it started to sludge in my rocker cover well before the oil change interval (1500 miles).
And even with an oil cooler fitted, it lost pressure on the track, compared to Castrol Formula R (now Castrol Edge Sport) 25W/50.
Graham Russell uses KMX instead of HPR30 for a reason- it's proved to be better. He has seen HPR30 break down during dyno runs.

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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.

I use KMX in the manual cars and castrol GTX in the autos. Seem to do the job. My 1100 clubman does about 200kms a week in peak hour traffic, and the KMX seems to handle that well

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88 Rover 1.3i "Reggie"
99 Rover 1.3i “Grover”
12 Mini Cooper S "The shitter"
17 Mini Clubman JCW “Noddy”