On the Toyota viscosity index, the indication says that you can run a 15w40 if the air temp does not drop below 20. I am running high zddp/phosphorus oil so hopefully my wear from the initial one second knock should be minimized.
That is a really good point regarding the smaller filter filling faster but isn't the anti drainback valve supposed to prevent just that. The Purolator oil filter that is in there now has an anti drainback valve and is still letting oil back. I was thinking that there is a problem with the oil pump seal allowing for the loss of oil in the filter. I will try a small Toyota filter next change, but if I still hear that awful noise, I am going to get deeper into it.
