I'm planning to buy a GT 500 and recently found out that all Shelbys require 5W50 oil. I have been using synthetic oil for more than 20 yrs and wouldn't even consider using conventional oil at all. The problem is that neither Mobil 1 nor Royal Purple sell 5W50 oil. My question is if I can use 5W30. Will that void the warranty? Will the engine suffer premature wear and tear. What about oil consumption. Are there other negative ramifications or consequences from using 5W30. I'm looking to maximize mpg. Thanks for the answers and sorry if this question has been asked before.

 

Only use the 5w50 oil. Motorcraft 5w50 is a fully synthetic oil and should be available at any parts store.

 

I run Schaeffer supreme 9000 5/50

 

Ford specifies 5W50 synthetic motor oil. Mobil 1 does offer 5W50 and I understand it is available from NAPA with part #98HF24; but I have not confirmed.

 

I just bought a bottle of Mobil 1 5W50 at NAPA for $5.79/quart ... on sale through March. Not all stores carry it though.

 

My experience is that MC 5W50 is only available from the parts department at Ford dealers.

 

Unleashed Beast on a couple other forums is very knowledgeable when it comes to oil. He has posted countless diagrams and spreadsheets. Most people consider him the oil expert. Whenever someoen has a oil question, people post about how he'll chime in and give the correct answer. I just put Amsoil 10w-30 in mine, and it is working great. Take a look at this thread. There are many more threads he's posted about oil, but this is the first one I saw:

http://www.svtperformance.com/forums...-oil-poll.html