Just out of interest, found the current specifications for maximum amounts of additives to achieve API ratings. P is phosphorus, Zn is zinc, and B is boron. Each figure is total parts per million of additives. These can also be roughly expressed in percentages by multiplying by .0001 (1301 PPM = .13 percent, 994 PPM = .099 percent)
API P Zn BSJ 1301 1280 151
CI-4 1150 1374 83
SL 994 1182 133
CJ-4 819 1014 26
SM 770 939 127
The following is comparison with Penrite HPR 30 and their Classic
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So the Classic is sitting at 1670ppm which is getting up there, but safely under the 2000. not a lot over the HPR30 though. Haven't compared prices. I'm meeting with an old mate that is in the automotive oil business tomorrow, be interesting to see what he thinks - and what he sells.