Its a 91 F150 4.7 v-6

For about a month now i have been hearing really nasty noise comming from my engine it sounds like things are rubbing togeather (maybe valves??) when i accelerate (esp in 3rd and 4th gear) i finally got sick of it so i checked my oil yesterday and it was very low (just changed it a coupple months ago) so i went to and baught 2 bottles of oil and put it in but the noise has been getting worse even with the new oil and i just realised that i put the same oil in (10w-30) as i did when i changed it but i axadently got the "high millage over 75,000" even though the truck has 150,000 on it but the problem is when i changed it i put the "high millage over 3,000" stuff in is that a problem? and after i put the two bottles of oil in there i checked my oil and it was past full but the oil looked very runny on my dipstick and it had some bubbles in it. ehh can anyone help me with what that sound might be, and if that oil is ok? i would really appreicate it.

Thanks

 

Well first off I didn't think they put V6's in the f-150's in 91. Isn't it just a 300 inline 6? If that is the case there isn't much that can kill those things. How low was 'very low' and how long did you run it that way? Being overfull is actually harder on the engine than being a little under full. It can cause high crank case pressures and other assorted problems. As far as the oil goes, as long as they are the same weight there shouldnt be a big problem but if it were me I would drain it good and then refill with one particluar brand and type because the additive packages are different between brands and types of oil (high mileage etc.) I would also check the oil for any metal that might be a sign of engine damage. It could be a collapsed lifter or a rod knocking if it was really low. Try that and then I would say move on to other more drastic measures if that is not the problem.

Hope that helps some.

 

HEY, DURA LUBE UR ENGINE BEFORE YOU EVEN THINK ABOUT STARTING IT UP AGAIN. I'M NOT SAYING THIS WILL HELP, BUT MY FRIENDS DAD PUT DURALUBE IN HIS 300 6CYL, AND HE DIDN'T PUT SOMETHING BACK RIGHT, AND ALL THE OIL IN THE CRANKCASE CAME OUT. THE ENGINE RAN AROUND ALL DAY, AND NEVER RUINED ITSELF. THE DURALUBE SAVED THE ENGINE, AND THE TRUCK RAN FOR 2 YEARS AFTER THAT, BEFORE HE SOLD IT. THE ENGINE WAS STILL RUNNIN LIKE A CHAMP