Sorry if this has already been asked (I searched and didn't see that it had been). My 2007 F150 Harley ed. Has developed a slight shake/ hop when going down the road. Gits new tires and it is still there so I checked the different. Oil level. I noticed it was a little low so I bought the correct Royal Purple and put in it hoping it would go away but it did not.

My question is does it hurt anything to mix the RP with the factory fluid? Also if anyone has any ideas as to what the issue might be I would love to hear. Truck has 90k and is all original except for running 305 tires. Thanks

 

Probably would not hurt, but at that mileage, it is definitely due to have oil replaced. Drain it put in the proper fluid (75w140) and make sure you put in the Ford friction modifier if it is a LS.