What's the best oil for YOUR Shelby, answers within.

[Kraftsman]

What is the recommended oil for a stock gt500 of the showroom floor? I drive a highly modded gt and 5w20 is recommended stock. Why do they call for such a light oil? I was told to run 5w30 but I like the idea of running a heavier oil with 18 lbs of boost and making almost 700 rwhp.

sent from my Droid Incredible

 

[UnleashedBeast]

What is the recommended oil for a stock gt500 of the showroom floor?

Ford recommends Motorcraft 5W-50, or equivalent. I recommend a robust true synthetic 20W-50 or 10W-40, depending on what your uses are for the car.

I drive a highly modded gt and 5w20 is recommended stock. Why do they call for such a light oil?

CAFE laws, and no other reason. It's a money game. Read more about that here.

Efficiency thread - CAFE laws

I was told to run 5w30 but I like the idea of running a heavier oil with 18 lbs of boost and making almost 700 rwhp.

In a 4.6L GT or Terminator, I agree with a robust 5W-30 or 10W-30.

Honestly, I don't think Ford ever intended on using a 50 grade lubricant in the GT500. Since 5W-50 easily shears to a light 40 grade/heavy 30 grade lubricant, it leads me to believe they actually call for a 40 grade lubricant. This is why I am current testing a 10W-40 in my GT500. I've posted UOAs from my personal car after using 20W-50 and 10W-40.

 

[Midnight00SE]

Seriously, a huge thank you for doing all this testing. It really is pretty amazing to be looking at a variety of manufacturers, viscosities and weights.

 

[UnleashedBeast]

This wont end anytime soon....still plenty of testing to do.

Also, I forgot to hyperlink the link above. Take a look at the CAFE thread.

 

[csullivan]

Mobil 1 5W50 is the bomb!!!!!!!!!!

 

[UnleashedBeast]

Mobil 1 5W50 is the bomb!!!!!!!!!!

It shears just as fast as Motorcraft and Castrol 5W-50, and has the same lower levels of ZDDP. Its no better than the other two. It also has comparable NOACK Volatility, and this means it will burn off/evaporate more. This will leave more oil vaporizing and collecting in your catch can, or air intake/supercharger intercooler.

 

[bigpappy33]

Just put in 10W40 amsoil

 

[2k05gt]

I had the same results in my tests, I found that Moble 1 oils are not much better than Dino oils. I did tests with 100% Synthetics like Royal Purple and Amsoil and these oils are far better, I have no issues using a 5W-30 Royal purple off the shelf at walmart or Advanced auto.

 

[Cobra SS]

It shears just as fast as Motorcraft and Castrol 5W-50, and has the same lower levels of ZDDP. Its no better than the other two. It also has comparable NOACK Volatility, and this means it will burn off/evaporate more. This will leave more oil vaporizing and collecting in your catch can, or air intake/supercharger intercooler.

looks like the Mobil 1 is getting returned tomorrow

 

[UnleashedBeast]

I've been performing pressure testing with Amsoil 10W-40. It's suitable for street use with colder thermostats, but still more oil pressure than required. I downgraded to Amsoil 10W-30 and now the oil pressure is perfect. I will have a new UOA on Amsoil 10W-30 soon to see how it compared to anti-wear versus the other Amsoil lubricants I have used.

I now reserve the use of Amsoil 10W-40 (street use with stock thermostats OR road raced with cooler thermostats) and 20W-50 for severe session road raced Ford modular engines. This doesn't mean you can't use 10W-40 on the street though, as it performed very well in my GT500 for over 4,000 miles. I have two great UOAs using it (stock and a 170* thermostat).

 

[Gabe]

I'm leaning toward the Amsoil 10W40 but I'd like a "5W" oil closer to what Ford recommends ... Would the Amsoil 5W40 work well in my 5.0 which Ford recommends 5W50 for ?

 

[UnleashedBeast]

I'm leaning toward the Amsoil 10W40 but I'd like a "5W" oil closer to what Ford recommends ... Would the Amsoil 5W40 work well in my 5.0 which Ford recommends 5W50 for ?

It's normal to assume that a "10W"-40 will have lesser cold flow performance compared to "5W"-50 Motorcraft, however....

SAE numbers on the outside of an oil bottle are very misleading. 5W-50 Motorcraft is actually a 20W-50 above 32*F.

Amsoil 10W-40 has far superior cold flow properties. The difference is quality of base stock used. True synthetics thicken less as they cool compared to highly refined petroleum (which Motorcraft is).

Amsoil 5W-40 European isn't as robust of a formulation.