After many years using Castrol CRB50 (no longer available) and BP Corse 50C (and occasionally Corse Plus - multigrade) have discovered Castrol Sport Edge 25W-50 and have just put the first lot in my 750 GT (currently 86,000 km, engine never been apart, oil changes every 2,000 km, owned since 1975). The Castrol tech guys in Melbourne were very helpful and seemed to have a good understanding of the requirements of Ducatis and older vehicles for which a straight 50 grade oil is/was recommended.
See
http://www.castroledge.com.au/product/product_25w50.php
From the downloadable pdf Product Data sheet at
http://www.castroledge.com.au/downloads ... 200601.pdf:
"Castrol Edge Sport 25W-50 is a high viscosity, high performance petrol engine oil formulated to satisfy modified engines, including older technology street machines and “big bore” competition engines. This oil is also recommended for large inboard power and ski boats, 4-stroke motorcycles, and high performance V8's.
Castrol Edge Sport 25W-50 is a premium quality SAE 25W-50 engine oil. It has been specifically formulated to give better cold start performance than traditional "straight 50" oils. It is race proven for power and performance.
Product Application
Ideal for:
• "Big bore" 4-stroke motorcycles; e.g. Ducati, Harley-Davidson, Laverda and Moto-Guzzi.
• Competition use.
• Veteran motorcycles and motor cars where high viscosity oils are specified or required.".
• Resists viscosity breakdown at high temperatures giving higher viscosity at extreme temperatures than traditional "straight 50" oils.
• Synthetic components increase load-carrying characteristics for crankshaft bearing protection in older technology street machines and “big bore” competition engines.
• Formulated to give better cold start performance than traditional "straight 50" oils.
OK - so it's all from the manufacturers blurb but I believe that Castrol knows a thing or two about engine oils. We'll see ....