Ford Dealers who use Castrol, I am told use Castrol FMX which is synthetic, not available to the public, I intend to use Castrol Magnatec 10w-40 as advise by Castrol and Ford Dealer. Have currently in motor FUSCH Performance Plus, appears to be good oil has synthetic additives, am using to flush out any crud. Interesting that a Turbo dealer recommends Castrol GTX3. What oil do others recommend. 15000 K's is to long between changes. When looking at Tech Data Sheets on oil's look at the ACEA rating, A1 Fuel Economy Petrol A2 Standard Performance level A3 High Performance and / or extended drain. B1 Fuel Economy Deisel B2 Standard performance level B3 High Performance and / or extended drain B4 For direct injection passenger car diesel E1 Non Tyrbo charged light duty E2 Standard performance level E3 High Performance extended drain E4 Higher performance and longer extended drain E5 (1999) High performance and longer drain plus American/Api performances. GOOD READ is Engine Oils what you need to know, www.chris-longhurst.com/engineoil_bible.htm1 Regards xrhp6