2500 miles on GTX

[jorton]

99 F150 4.2
With 2500 miles on the 10w30, the motor now idles and runs smoother and quieter than when the oil was fresh.
But when I start the truck the motor cranks slower. I think it takes the same number of revolutions to fire, but just about 1 second longer.
Should I stay with this oil, or switch to 5w20?

 

[Durrr]

10-30 is just fine for a V6, but, if you think it'll make a difference, try it and see how you like it. If you don't like the results, then switch back

 

[crashz]

I'm not quite at 3K on my fist fill of Royal Purple 5W-20 (01 F150 4.2L) and I can tell you it runs rougher and seems to have lost power. The truck ran the best on 5w-30 QS or 10w-30 M1. My next oil will be Amsoil 5w-30 because I think it may be just the right viscosity.

The 5w-20 has given me a bit of a mileage boost, but nothing extrodinary.

 

[Virtuoso]

I bet you could do either oil with good results, but I'd stay with 10w-30..and I'd bet your cranking issue is something other than the oil.

 

[andyfish]

Oil is not the only reason for an idling issue etc. In the grand scheme of things that could be wrong I believe its minor to mute. Maybe the battery is going and it cranks slower?

 

[jorton]

Yea....it could be the battery. When the battery died on a trip 3 years ago I bought one from a private individual that had a lower amp rating.

Right now it's only cranking slow when the motor is cold.