1. Don't know what kind of oil the person prior had been running but just did heads and such and want to go Mobile 1. Good or bad to make a switch so late?

2. I have stock 18" wheels with 255/55/18. What tire perssure do you all use for front and rear or just use MFG reccomended per the door sticker?

 

Switch to mobil 1 5w40 TDT and be done with it. Ignore any slight leaks or weeps for the first couple oil change intervals (at least 5,000 miles and probably more with the TDT oil, though you may want to change your oil filter at 2000 miles for the first OCI as the HDEO will clean up a bit).

 

I run 40 psi all around and let the front down to 35 if I expect alot of ruts and such.

 

I ran at 40 psi but with the medium OME springs that is a rough ride. So I backed down to 35 and it is still rough. You would probably be fine with OME type springs or air bags to go 40 all around.

 

Auto Zone has a sale on 5 quarts of any Mobil 1 and a Mobil 1 filter for $29.95, go take advantage of it, use their 301 extra long filter.