I had trouble finding 90-140 oil as specified for Lofrans windlasses in their Oil Capacities (http://www.lofrans.com/documents.php?categoryId=3) document.
I was advised by the Lofrans UK Distributor (Peachment) to use Morris Lubricants product Lodexol XFS 80W-140 Gear Oil ... a fully synthetic gear oil that has been formulated with high levels of extreme pressure (EP) additives and friction modifiers to protect the critical mechanisms of limited slip differentials.
I then saw Fully Synthetic 80W/140 Limited Slip Differential Oil 1 Litre GL-5 (http://www.ebay.co.uk/itm/121731717459) on eBay and asked the seller if this was compatible with the Lodexol XFS. The reply from the eBay seller, westwaylubricants: Funny enough that is exactly what is in our bottles. We buy in bulk from Morris's and decant to smaller bottle.
This is their web site: http://www.westwayoils.co.uk/ (http://www.westwayoils.co.uk/)
URL got mangled, this one? http://www.ebay.co.uk/itm/1L-Fully-Synthetic-80w140-80W-140-Limited-Slip-Differential-Oil-1-Litre-GL-5-/121731717459
Thanks for figuring that out, saves me the trouble! :tbu