I have now found Sean in San-Francisco! I am told he has a vast array of British Seagull spares. He will have his web site up and running soon, in the mean time he suggests you telephone him on 415-861-6124, between 8 and 4 his time. I understand he is better with a phone than with e-mail etc....
His web site address is www.britishseagulls.com click the button below to see if he is on line yet.
For 140 oil in the States try 'Amsoil'. Bruce Chadwick is an SOS Spares customer! click the logo above.