2500 miles on GTX

Messages
3,118
Location
San Antonio, TX
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?
 
Messages
188
Location
Charleston, SC
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 [Big Grin]
 
Messages
656
Location
Massachusetts
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.
 
Messages
2,703
Location
Lincoln, NE
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.
 
Messages
143
Location
NH
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

Thread starter
Messages
3,118
Location
San Antonio, TX
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.
 
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