44mille

First of all, greetings to Mustang Forum!
Now my question, I bought a 40h Anniversary GT, 4.6 Liter Mustang a few months ago. Now, I'm not exactly car performance savvy but do all of my own maintenance on my cars. I was servicing the mustang on Saturday and changed the oil. The recommendation for oil weight and viscosity is 5W20, I bought the oil that day and placed it on the shelf next to my trucks oil, 10W30. When I was putting the new oil in the car, I noticed that I had used the 10W30 instead of the 5W20. I know this is about the dumbest mistake, but I left the oil in the car. My question is, since the MFR. recommends 5W20 should I drain the 10W30 because it could damage the Piston rings and cylinder walls on colder starts?
Somebody please make up my mind for me!
Thanks,
Eric

mdvaldosta

both work fine, Ford recommends 5w20 for fuel economy reasons - not because it protects better than 5w30

redmustang

I did the something similar.
MDValdosta...i put my wifes oil in my car one time, someone told me it didn't matter, so i changed both our cars at the same time by buying a big case.
when i did the next oil change 3K miles later, i put the suggested 5w30 or 20....my motor felt bogged down. couldn't chirp 2nd no matter what. any idea why i would lose power???? i now am at the 53K mark and wonder if i should start using a different oil?

mdvaldosta

oil weight does make a small difference in power... but 5w20 probably only makes maybe a half hp more than 5w30 (speculation, I don't know the actual amounts but its very small). You definately won't be able to "feel" or likely even measure the difference. Now synthetic oil would likely make a couple hp difference... still not something you could feel though

tulsastang

unless the weather is very cold out. You will probably be ok. I would lose the 10w weight though the #1 reason ford recomends 5w20 is for the overhead cam set up. Your owners manual will state using a different weight oil will cause start up rattle which mine did.

I switched back to mobil 1 5w20 things are back to normal now. While your car is under warranty you are better off using the recomended 5w oil or risk being voided.

Guest

Read up. You'll be just as smart as MD.

http://www.vtr.org/maintain/oil-overview.html