Hey all,

I have been running M1 5W30 for 99K of the 114K miles the truck has on it, and was thinking about making a switch.

1. In the past with older cars, as the mileage gets higher, as a rule of thumb (or at least how I was taught) you start going up on weight. So if you started at 5W30, if you reach 200K you should be using something like 10W40. Does this hold any truth with synthetic as well?

2. Could I conceivably switch to Motorcraft 5W20? A mechanic at the Ford dealership here recommended not to due to the high mileage on the truck and the buildup/deposits that have resulted from running M1 for so long.

Any help would be appreciated. Thanks in advance.

 

Are you using oil now, is it more than it used to, if not why change.

 

The only reason I started using heavier weight oil in our old car was because it would burn off the lighter weights too quickly. If not for that I would still use the lighter weights in it.

As said, unless theres some reason to switch, keep using what you have been using if there are no problems.