Is this oil appropriate all year around in Minnesota? It seems like the viscosity may not be high enough for a B230F non-turbo with 90K miles on it. I just replaced the head gasket, main seals and cam/intermediate seals and the crosshatch can be seen on the cylinder walls but I have a hard time believing a 0W-30 oil will be good in 100 degree fahrenheit weather in the summer down to -30 degrees in the Winter. The engine just went into a 740 after the original engine died with a broken Intake Valve (any idea why this would happen?). The engine is a type-L with oil squirters (really quiet compared to the type-K engine).

Amsoils response to this question (I said I did 20K miles/year) is:

Thank you for contacting AMSOIL with your concerns.

In response to your inquiry, the Series 2000 0W-30 would be the best oil for this application. It would be rated for one year drain interval, with the oil filter being changed at six months.

Thank you again for the opportunity to respond to your concerns. As always, please feel free to contact us again if we can be of further assistance.

Sincerely,

Name Deleted
Technical Service Department