I have just rebuilt my 3l engine for the second time! Made a few improvements and was looking at oil again. Started on penrite light 20/60 give 40- 55 psi depending on temp, but it's only by mail here,£36.00 for 5L. Found a few new ones and I found info on some old ones. Duckhams new "classic"Q20/50 1300 ppm ZDDP 29.99 5l Fuzz Townsend's Classic oil 20/50 1300 ppm ZDDP 19.95 5l Westway lubricants classic 20/50 1500 zinc 1450 phos 2900 sulphur 24.99 5l Morris classic 20/50 about 1000 ZDDP All the Millers classic pistoneeze are between 1000 and 1100. So all classic oils are not the same! On reflection I will pay the £36 for the penrite 20/60. Just wanted to share the info.