I agree that straight weight 30 engine oil is the best for the summer months in the midwest climate, with 10W-30 for the winter months. Years ago my Dad was a mechanic for a bus company. He had to keep rebuilding the bus engines. Then they switched from 10W-30 to straight 30, and the engine rebuilding went to practically zero. The 30 weight provides significant cushion between the rod bearings and the crankshaft that a multi-viscosity cannot provide. If you like to rev your engine, use the 30 weight. Best regards, Jim -----Original Message----- From: Gary Nelson [mailto:Gary@xxxx] Sent: Wednesday, July 10, 2002 4:51 PM To: Rusty and Thelma Roe; Chrysler300@xxxxxxxxxxxxxxx Subject: Re: [Chrysler300] 57 300C Stuff Rusty, I have learned that a good single viscosity oil is best, like 30 wt. If car has plenty of miles and the fact that it is summer I would use 40 wt. I can not remember the specific reason a multi viscosity is not recommended. Maybe someone one the server can pick up on that issue. As far as ATF, although Mopar calls for Dextron II, Type F is the preferred oil. It is less slippery and works better with clutches and bands. This is obvious. Make sure they drain the torque converter also. Good luck on that trip. Hope that A/C is up to snuff. At least I know you have a spare water pump.