I mixed regular gas and E85 in my Intrepid and it didnt do any harm at all, no difference in mileage either
But it's not for sale around me so I only added it the one time
Code P0420 is a code for Catalyst efficiency. The computer is seeing the post Catalytic converter o2 sensor having too much activity. The Cat. should be cleaning the exaust of Hc, co, and Nox. The post cat o2 will read the o2 content in the exhaust and if it moves up and down too much or to high...
it is low
Pull the oil fill cap - wipe off
reinstall then check it's level.
A oil change would probably be a good idea if it needs oil, might as well replace it!
bottom side of crank - in front of the engine - near the timing chain cover
A deep well socket 3" extention and a 1/2" ratchet are all you need to take it off
The same deep well socket, thread tape, torque wrench are all you need to replace it
the rear springs are not setup for that much weight.
You can add a "helper" spring to carry the load, but you will still have sway issues.
PS - you didnt offend me!!!
spark plugs:4.00 each (you need 6) 24.00
spark plug wires - 40.00 - 85.00 - - - from chepies to premiums
Only 1 hour labor at 45.00 per hour mechanic normal.
So about 150.00 would be a better estimate. This is very easy to do, all you need is: a spark plug gapper a 3/8" ratchet-6" extention...