I have been using 40 grades for the last 3 years on my 2018 5.0 in an F150. May just start using 5w50 as well. Just recently I replaced my vct solenoids due to a rough idle and stalling issue. Which seems to have fixed the issue so far. Warranty did not cover these as I had no check engine light / codes. So I paid out of pocket. Some things I’ve seen in datalogging is that using lighter oils you get really low psi at hot idle. Which doesn’t allow for the vct system to operate properly causing issues. I’ve found that heavier oils give higher hot idle pressure and it runs much smoother. Here’s some info I have saved from a well known tuner for these.
The noise is not coming from the DI pump. It is being caused by the DI pump, but the noise itself is typically the exhaust cam phaser on the passenger side. The added load of the DI pump and the stiffer valve springs in Gen 3 motors put a lot of extra force on that cam.
At very low loads and RPM, the oil pump is barely making 20-25 psi of oil pressure, and very minimal flow. So, then the VCT solenoids open to allow oil to enter the phasers to rotate the phaser, there isn’t enough pressure or flow to fill the galley quick enough to rotate the cam, and there’s a small amount of air inside the phaser for a split second, while the cam is being commanded to rotate. That causes the phaser to “rattle” back and forth until oil fills the galley and rotates the phaser. Is it ideal, no. Is it hurting anything, highly unlikely.
Now... why does it happen tuned and doesn’t happen stock. That’s because in our tune, we schedule the DI system to come online earlier, at lower loads and lower rpms. We do that, because this being a 12:1 CR engine, it needs all the knock protection it can get, especially if you choose to run low octane fuel. Direct Injection direct cools the cylinder, greatly increasing knock protection and performance. So, it’s a valid trade off. Better protection from something that definitely will hurt your engine, knock, versus the slight chance that if you feather the gas pedal juuust right, you’ll here the cam phasers rattle.
Let me be very clear this is not “ping”, “knock”, or “detonation” like everyone likes to describe any noise they ever hear an engine make. Trucks that have this issue will make the noise even with E85 in the tank, and it’s essentially impossible to cause knock on one of these engines on E85, without obscene amounts of boost. So.... it’s not knock.
Another easy test you can do yourself to prove to yourself, that “maybe” I might actually know what I’m talking about.
When you hear the noise, press the pedal down just a little more. What this will do is instantly increase oil pressure and flow, abs the noise will stop. Now, if this were knock, increasing load would have the exact opposite effect. You would cause more knock because the cylinder pressures would increase with the added load/throttle.
Lastly, for everyone that’s hearing this noise, you should all check your oil levels. Everyone knows these trucks have oil consumption issues, and of the dozens of times I’ve explained this to various people 90% of the time the person complaining of the noise was down on oil.
So, things you can do to improve or eliminate the noise. First, make sure your oil level is full. I personally run an extra 1/2 quart of oil in all of my Coyote engines. I do this based on recommendations from several well known engine builders. Coyote engines tend to have a hard time with oil drain-back when driven hard, and that can leave you with an oil pan that’s basically dry at WOT. Adding an extra 1/2 quart is a good way to help with that, and have adequate oil flow will also help with this noise. Second, run 5w50 oil. It’s perfectly safe for any Coyote engine, and the added weight can increase oil pressure at low loads, which can help with this problem as well.
More info to share. I've touched on the tip-in "rattle" a few times, and what cuases it. It's often mistaken for knock, but it's not knock. The noise is coming from the VCT system, and is typically the timing chains slapping against the guides. Ford has issued an SSM for the noise.
Reading through the SSM, you'll see that the very first troubleshooting step is to verify oil level, as low oil level will cuase the VCT system to not have enough flow or pressure to proeprly actuate the VCT phasers at low RPM/Load. I would add onto this further and also note that we recommend, and use, 5w50 weight oil in all of our Coyote engines. The added weight will increase oil pressure under the same operatring conditions versus Ford's recommend 5w20 weight oil. Before anyone attacks me for recomending "non-recommended" oil weights. You should know that any high performance version of the Coyote (Boss 302 and 302S for example) and also Roush, who sells vehciles at Ford dealerships with full factory waranty, both recommend using 5w50 weight oil. So, any one experieincing a tip-in rattle at low RPM/Load, might want to consider these troubleshooting steps.
To further add to this, the range to fault the DTC codes mentioned in the SSM seems to be pretty large. I have seen datalogs from several trucks with VCT control issues that are not faulting these DTC codes. Most of them are easily sorted with switching oil weight and making sure the oil leve is full at all times, but some have actually required repalcing the VCT solenoids. It would probably be difficult to get the solenoids repaced under warranty without the DTC codes present, but for those experiencing rough idle, stalling, or tip-in rattle, the info in this SSM could be benficial.
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https://www.tsbsearch.com/Ford/SSM4...b2PIlEKjE04jIh8Td8Uo_9DQkvzCR0LR7pApnjCsfYbk)
