I lent my truck to a very good friend to use over the weekend.
He checked the oil when filling it up with gas to return to me and added a quart of Castrol 10W-40.
He was correct in adding Castrol but should have added 10W-30.......
How much is this an issue? Do I need to change the oil asap or can I let it go for a 1000 or so miles until the oil needs changed.
Thanks for your expert advice and thanks for this great forum!