Thankyou Phil and Thankyou Big Dean

We've never used the weight figure over here, we've only ever used the viscosity figure. So SAE 90 weight oil to you is between 40 and 50 SAE viscosity to us. Hence the difference in the manuals, and also hence the confusion on the oil grade.

Universal grade tractor oil over here will provide the correct viscosity and lubrication required, as will 'straight' SAE (viscosity) 40 i.e. oil with no detergent additives.

Therefore we were both/all correct in what we were saying, it was just that the methods of measuring the type/grade of oil differed.

D#mn, talk about a common language separated by 200 years and 4000 miles!!

Job done, no further comment on this - it's been done to death by us all - but thanks again, I can now sleep easily knowing my gearbox is safe.

Phil Fenner