mcburns36

Running 10w30 in my 07 GT since new . NO issues .

DavidIX

The 10w-30 I have right now is the dominator racing oil by Amsoil.. I'm sorry if I did not point that out in my original post.

Either way I just went ahead and got Amsoil 5w 20 XL Synthetic. I guess we'll see how it performs. Thanks for the help anyways.

everett

Well at least it was amsoil...unleashed beast is our resident oil expert. His word is gospel when it comes to oil. I have subscribed to all of his oil threads. The guy knows what he is talking about

JIM5.0

I went to the store the other day to pick up 8 qts of RP. I asked the clerk if he had any RP in 10W30 & 5W30. I also asked him why do car makers force 5W20 on us. He didn't have a damn clue. All he could say is "Engines today have much higher tolerances (less moving parts clearances) and a lighter oil is needed to get into those spaces."

Sounds like BS to me.

I wound up buying 5W20 because that was the only one he had enough of for 8 qts. Everyone else bought up the 5W30 and 10W30 oils.

Unleashedbeast

Really? No offense, but leave the oil debate to the pros.

Original Poster,

Take a look at the viscosity chart below.



This is a viscosity comparison of Amsoil 5W-30 (ASL) and Amsoil 10W-30 (ASM).

I'm not comparing a 5W-20 lubricant here, because I'm blue in the face explaining that was for CAFE laws, and no other reason. I recommend a 0W-30 or 5W-30 lubricant in a non-supercharged 4.6L 3V engine. For a supercharged application, a 10W-30 is fine, and won't make a hill of beans difference in warmer climates. The viscosity of all three grades will be very close to the same at 100*C.

You live in Arizona. The climate there is very warm in the summer. Notice how close in viscosity both fluids are from 30*C (86*F) up. You car would never know the difference, but I can assure you that the 10W-30 will resist shearing better than a 5W-30.

Use what you have with confidence in your climate.

Unleashedbeast

Dominator Racing RD30 (10W-30) lubricant is slightly more viscous than their ATM 10W-30 100% synthetic. It also has much higher concentrations of ZDDP, but doesn't have as high of TBN (detergent additives). This means you wouldn't want to use it as long as their street formulations.

IMO, you made a bad choice (between the grades of Amsoil). Not saying you can't get a solid 5,000-10,000 mile oil change interval from this, but the base stock is inferior to the Amsoil ATM, and the viscosity is less than you really require in a hot climate like Arizona.

Next time, try their 5W-30 (ASL) or 10W-30 (ASM) for optimum performance and wear protection.

Amsoil XL and OE line up are the equivalent of Mobil 1 supersyn and Castrol Syntec, so no harm no foul.

Unleashedbeast

It is BS, or Ford wouldn't have back spec'd engines to 5W-20 that were formally spec'd for 5W-30. The tolerances didn't change, CAFE laws are in effect, and the auto manufacturers decided to make the change for profit increases. The sacrifice saved them millions in penalty fines to the US government.

Also, the same Ford engines manufactured today that are used in Australia are spec'd for 5W-30. Want to know why? No CAFE laws in Australia.

2007CalSpec

Very informative! I've always ran Mobil1 5W-20 synthetic. My car has about 44k mi. on her and 8k of that is supercharged miles. I'm going to switch to Royal Purple 10W-30 tomorrow after reading this thread.

Socal6r

bump for more input, i enjoy reading all the comments, experiences :P