I run a 2001 Merc 250 EFI. I have been faithful in having it serviced each year - plugs, filters, lower unit, impeller, etc. and have always used premium plus oil. Last year I brought "premium plus" from a bulk tank. This year when the engine was being serviced, the mechanic called to say that the oil had "geled" & was stopping up the filter and I would have probably blown the engine if run much more. Close call. Be aware when you buy bulk oil. Mixing oil types or using off "the bottom of the tank" could lead to disaster.