10w40

[bob8492]

Is it ok to use a lighter weight oil in my 99-F350 for winter? I use 10w40 now. If so, where can I buy lighter oil and what kind??? Our local auto store only has 10w40. Also, if there any benefit to vaccume out the injector pump and change that oil. I have always changed the engine oil before 5000 miles. This lighter weight oil needs to be Diesel oil right?
thanks.

[Rob]

i believe you should be using a 15W-40 in the summer months and a 5W-40 in the winter for easier starting. i have always done the 15W-40 year round but am going to change on the next filter swap...