What oil weight?

[Tripoli]

First of all, I tried searching for this topic, and much to my amazement, the keyword "oil" comes up with no matches on this forum.

My 2002 Mustang GT recently passed 100,000 miles. The past 98,000 or so have been with Mobil 1 5W-20. I live in Texas. I've had no problems whatsoever with the motor. I daily drive her and take her to the track about once a month. She regularly sees 6,500 RPM.

Should I stick with 5W-20, or should I change to something like 5W-30 or 10W-30?

 

[CobraRed_96_GT]

Since your getting up into high milage and you dont see extream cold - i'd definitly recomend a synthetic 10w-30. It not too thick in the least, and is exellent (by most manufactureres) in flash point and heat break down deturances.
I stick to Mobil 1, Kendall, and Royal Purple. Cuz those are the ones that wern't afraid to send me temp/pour/flash specs when i worked at Royal Petroleum. Based purely on impresivness of tech sheets, id say Mobil 1 for engine/tranny and Royal Purple for coolent/differential ( i havent seen Royal Purple tranny oil specs yet tho)

 

[Dragstr05]

The 5w-30 is a little thicker. I usually get 5w30 or 5w20 whichever is available. The 4.6 originally called for 5w30 but Ford started calling for 5w20 for improved fuel economy.

 

[Skidawg]

As long as you're using good quality oils and have had no issues, I don't see any reason why you should change weights. You can, but it's not going to make much difference...