Cool thanks bud!

 

You are all missing one major point here when it comes to oil viscosity. The reason the Shelby's and Boss engines spec the 5W50 oil instead of the 5W20 is for a multitude of reasons. First, and most importantly, is with the bearings used in these performance engines. Ford purposely uses a set of crank and rod bearings that are "looser" than standard bearings. This frees us some horsepower, but needs a thicker oil to keep the crank journals floating over the bearings. On a standard 5.0, it is built with bearings that are tighter and require the thinner oil... if you were to use a thicker oil, there could be some issues with getting proper oiling into the engine bearings.
The other thing was mentioned a few posts prior, and that is with the operation of the TiVCT. That is regulated by oil pressure, and the thicker oil in the system will run at a slightly higher pressure. This will effect when/how the TiVCT will actuate and potentially change the performance characteristics of your engine.
The third reason 5W50 is used in these performance engines is to take advantage of it's higher heat capacity. The supercharged and Boss motors typically will see higher operating temperatures (on track) and the higher viscosity oil allows for some head room for the oil to heat up and drop to a lower value, while still offering adequate protection for the bearings.

In a nutshell, use the oil weight called for in your manual. That will yield the best results for your engine in the long run.

 

Not true but think what you want.

 

http://www.svtperformance.com/forums...etic-oils.html

 

If you want to understand the engineering done in the Coyote 5.0 engine to make it work properly with 5w-20, it's woven throughout this article:

http://www.mustang50magazine.com/tec...e/viewall.html

5w-20 non-synthetic was the lubricant that the engine was built around, and unlike earlier modulars, the design compensates for the lower viscosity with a larger oil pump and it takes advantage of the lower viscosity to keep the running temperatures lower.

The second article explains the changes that were made to transform the Coyote design into the Roadrunner Boss 302 engine. There's a good explanation of why they upped the viscosity to 5w-50 and switched to a synthetic oil:

http://www.mustang50magazine.com/tec...2/viewall.html

If you plow through both of them, as I've done a few times now, you'll eventually concluded that if you're running your engine consistently below 7000 RPM, then you can safely use 5w-20 (preferably synthetic) and your engine will work and last as the designers intended. Unlike back-spec'd 5w-30 engines, this one was built to use the lighter oil from the get-go.

On the other hand, if you're planning to run over 7,000 RPM, then there's an argument to be made for using a thicker oil, but keep in mind that a Coyote wasn't built for this RPM and durability issues can arise that won't be corrected by thicker engine oil.

There is one oil out there (that I've found) that combines the thicker bearing protection of an xw-30 oil and the flow characteristics of a 5w-20. Most xw-20 oils have a High Temperature High Shear viscosity around 2.6 to 2.7, while xw-30 oils are around 3.1 to 3.3. This viscosity measure is based on the high pressure and fast rotating conditions found in main and rod bearings, and essentially the higher the number the lower the wear.

The oil that is rated as 5w-20 but has the 3.3 HTHS of a 10w-30 is Redline 5w-20. It isn't labeled to meet Ford's specs (or even the API specs for that matter) but from a performance standpoint, it offers the best of both worlds. I've got a dozen in the garage and it's going in before next track day season starts.

 

I fairly recently purchased a garage kept 2010 Shelby GT500 which had under 5,000 miles and most likely was still on factory fill. When purchased, the dealer changed the oil because the car was in Chicago in January and was to be driven to Florida so even though the mileage limit was not exceeded, it was good to do before such a trip. The Ford dealership used Motorcraft 5W-50 full synthetic. The once garage bound car is now being driven every day by me just as if it were a Camry except it is a lot more fun. I am going to continue using Motorcraft 5W-50 full synthetic changed by Ford for the duration of my time with this car. I like it and I think this will go on for a while. Part of the quandry we find ourselves in is the lack of a large body of data or historical knowledge about some of the issues we question. If I had to hypothesize about engine damage if I stay within change intervals anytime in the near or not so near future. Time will prove me wrong or right. I am sooooooooo glad this car doesn't call for 5W-20. This is an iron block engine and maybe that oil is right for aluminum but I'm not going to provide unfortunate personal data/experience to help Ford determine a thicker oil might have been a good idea even if the car got 0.2 fewer mpg's....which I think played a major part in that particular oil's recommendation. I want a thicker oil at operating temperatures. If an oil can do that and still flow well during start up, we have ourselves a winner. I'm glad Ford called 5W-50 full synthetic for the Shelby and the Boss, and I'm equally surprised they say conventional 5W-20 is fine and you can go almost 10,000 miles before changing it. Am I wrong to expect a large company to back up its statements? Those are wildly different oils considering all are V8 engines for the same company line.

 

I,ve always stuck with the weight thats called for the car just synthetic.I use Mobil one 5 20 and if i change the brand it will still get 5w20.

 

just a warning to all. do not ever mixed different brands of synthetics. I have been told by an engine re builder that the chems react and can turn to an acid and eat away at the engine. Would hate to see that happen to anyone.

 

Say what? I guess I am about to find out if this is true and its not. As expensive as oil is these days I never waste a drop. I just finished changing the oil in my beater truck with 4.3 Gm v6 engine and the oil fill went something like this. 1 quart of mobile 5w30EP, 1quart of motorcraft semi synthetic 5w20, 1 quart of regular mobile 1 (blue cap I think) 1 quart of mobil 5000 regular 5w30, and the last haft quart I cant even remember but I think it was regular pennzoil. LOL What a mixture. I do this all the time when I get down to a quart here and a quart there. Never had an issue or noticed anything different.

 

I think this is it exactly. The Motorcraft 5W-50 tries to have similar cold start friendliness as something like 5W-20 while being able to withstand higher temps like a heavier oil when the engine is being run hard.

The 5.0 Mustang article about the Coyote engine does say that it generates a ton of heat when it is run over 4500 RPM for extended periods. This is where the 5W-50 would be necessary (the reason it is factory fill on BOSS302 and GT Track Pack).

I think for a daily driver car that will never see open track use, 5W-20 will do a better job of preventing cold-start engine wear. Plus you're changing the oil more often on a DD, 5W-20 is easier to source & much cheaper.

If you do plan to run your car on a road course, I think 5W-50 is absolutely the oil you want. And according to that article you probably want to consider an oil cooler too.

 

Just passing on info I heard from a expert guest speaker on engines and oil. I suspect that the universe will not explode in an instant but rather become unstable and relive the big bang down the line. Like anything you see on the forums it is always wise to follow up with more research and expert opinions before excepting or rejecting a post. Also not all brand may react. I plan to play it safe and use only one type. if I switch then I will flush first.

 

My understanding is that all commercial motor oils are compatible.

See #23 from Valvoline here.
http://www.valvoline.com/faqs/motor-...tic-motor-oil/

See "Can AMSOIL be mixed with other brands?"
http://www.amsoil.com/frequent.aspx

See "Are Royal Purple lubricants compatible with other motor oils"
http://royalpurpleconsumer.com/why-rp/faqs/

 

Well, I was in a pinch and couldn't drop car off at Ford for the day. Could not find 5W-50 no surprise, so I got Amsoil 5W-30 and will hope for the best. It was the highest quality oil I could find as none of the synthetics available were 5W-50. It says I can go 10,000 miles with it. I am at 13,500 miles figure I'll go to 20K then put Motorcraft 5W-50 in it. I'll plan it better next time. I think what I put in it will be fine this once.

 

I use amsoil 5w-30. But I change every 5k due to track time every week

 

You actually put a better oil in this time. And on my daily drivers I've used Amsoil and have put 20,000+ on before changing it. I use Amsoil 10w-30 in my Mustang and change it once a year.

 

After reading all this thread and the owners manual, I think I am going to use Motorcraft Premium Synthetic Blend 5W-20 and a Ford FL-500 S filter as recommended by Ford.

 

I wouldn't. Here's a good read on why many of us are running Amsoil 10w-30.
http://www.svtperformance.com/forums...oa-thread.html

 

I plan to run 5w50 (as recommended with track package cars) since it will see extended operation above 4500 RPM and the 5w50 oils are better suited for this. For the summer, I'll probably use race spec oil (higher zinc content, amongst other things) for the track days, then switch out to something more street friendly for the colder months. For street driving, I would think synthetic oils of various weights would be acceptable... my engine isn't technically different than the non-track pack ones as far as I'm aware, so it should be able to be run with 5w20 up through 5w50 (assume anything in between)

But I'm not an oil expert

 

Actually no 5w-50 is not better suited for you. I urge you to read the link I posted.

 

...because we all know, everything on the internets is truth.