I had a very interesting conversation with Richard Hallett of Hallett Oils yesterday
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(01902 710783); here's a summary that people might find useful:
- Tellus11=ISO5 and Tellus27=ISO32
- ISO32 can apparently be mixed with paraffin (approx ISO3) to give other viscosities; he can add additional additives to ensure that the dilution doesn't lead to an additive-deficient oil
- Dilution ratios (ISO32/ISO3) give the following results: ... 95/5=ISO27 ... 80/20=ISO18 ... 50/50=ISO8
- 5 litres of VG32 with "added additives" suitable for up to a 50/50 dilution was £12.31
- He has a wide range of other oils, tapping fluids, etc
Usual disclaimer: I'm just reporting what appears to be an unusually helpful and knowledgeable chap; I've no connection, YMMV, etc.
Dave