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Discussion Starter · #1 ·
Has anyone switched from 5W 20 to 5W 30 oil? I recently had the dealer instsall Penzoil Ultra Platinum 5W 30 oil and there are no ticks or rattles, etc. HOWEVER, at idle, about 7-800 rpm the oil gauge indicates about 17-18 psi but at 3,500 rpm it has jumped to about 80 psi and by 5,000+ rpm it is close to 100 psi.

Has anyone ellse experienced this? Or any other issues switching to 5W 30?

I am concerned the oil pressure is actually too high
 

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I switched on my CV to 5-30 some time ago due to the heat down here and after reading that it will increase the longevity of the motor. I have had no issues, however, I do not have an oil pressure gauge installed on my car so I don't know if it affected the pressure or not. I don't see how it will as the weight of the oil is unchanged, the additives are different, so if that somehow changes the viscosity, I am not sure how.
 
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Export 2019-20 Bullitts have a specification of 5W30, however, they also have a difference engine calibration. My shade tree mechanic instinct is to tell you that leaving it 5W20 is probably the way to go if you have concerns about any engine warranty claims being denied, if you were to need to make a claim. Don't forget the variable valve timing works on oil pressure, and it seems logical that changing the viscosity could impact what's in the system. Also, I believe 5W50 synthetic is specified if you are racing on a track. In short, will it "hurt" the engine? Without a detailed understanding of the oil pressure as a function of how it's involved with the variable valve timing system, I could not personally say.
 

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I have a 19 Bullitt and I recently changed to a 5W30 at 11k miles and I don't hear the rattles, also I have and app on my android called Torque and I can record video while I'm driving with all the gauges I want on the screen, my app connects to the OBDII via bluetooth and send the signal to my app and I can track the HP at the wheel in real time also Rear axel torque, while I was driving with the oil 5W20 my max HP was 450hp and 430 ft/lb and now with 5w30 I have 517hp at the engine and 492ft/lb, is quiet engine but strong in responds. the app ask you for all the info of your car, and need to be correct to have the real readings on the gauges, I recommend this App

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Discussion Starter · #5 ·
I was on the Mustang 6 site this morning and it is reported by members that Ford has changed the oil specs for the 2021 Mustang GT to 5W 30. I doubt Ford has made any internal changes to clearances etc so it would appear that 5W 30 is safe for our engines and is even recommended now. Of course Ford has not made any announcements that the change is retroactive to 2019 and 2020 Bullitts but we have the same engine as the 2021 Mach One
 

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Discussion Starter · #6 ·
Export 2019-20 Bullitts have a specification of 5W30, however, they also have a difference engine calibration. My shade tree mechanic instinct is to tell you that leaving it 5W20 is probably the way to go if you have concerns about any engine warranty claims being denied, if you were to need to make a claim. Don't forget the variable valve timing works on oil pressure, and it seems logical that changing the viscosity could impact what's in the system. Also, I believe 5W50 synthetic is specified if you are racing on a track. In short, will it "hurt" the engine? Without a detailed understanding of the oil pressure as a function of how it's involved with the variable valve timing system, I could not personally say.
Actually it is 5W 30 specified for track days

What determines the necessity for a particular weight oil is the engine internal clearances, especially the side clearances. There is little difference between 20 and 30 but 30 provides slightly more protection. Even though an engine requires only about 4 microns of oil film strength to protect moving parts that interact.
 

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I was on the Mustang 6 site this morning and it is reported by members that Ford has changed the oil specs for the 2021 Mustang GT to 5W 30. I doubt Ford has made any internal changes to clearances etc so it would appear that 5W 30 is safe for our engines and is even recommended now. Of course Ford has not made any announcements that the change is retroactive to 2019 and 2020 Bullitts but we have the same engine as the 2021 Mach One
To be absolutely safe, I'd see if it was retoractive to other model years...but that's just me being super cautious because I don't want to have any disputes over a warranty claim.
 

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Actually it is 5W 30 specified for track days

What determines the necessity for a particular weight oil is the engine internal clearances, especially the side clearances. There is little difference between 20 and 30 but 30 provides slightly more protection. Even though an engine requires only about 4 microns of oil film strength to protect moving parts that interact.
You are correct about track use as per the owner's manual.

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I've been running 5W-30 since my first oil change (about 6K miles so far) without any issues.
 

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Discussion Starter · #10 ·
If Ford approved the W 30 for hard racing it obviously has no effect, IMO, on lubrication, cooling, and variable cam timing. All would suffer under the harsher racing conditions but obviously do not
 

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If Ford approved the W 30 for hard racing it obviously has no effect, IMO, on lubrication, cooling, and variable cam timing. All would suffer under the harsher racing conditions but obviously do not
I know people have debated about Ford covering an engine failure used in a racing situation on various forums I've read over the years. I've seen claims be approved and denied. I've never seen a clear specification of what kind of usage would constitute an approved definition of racing, but I presume Ford would have done some level of testing. To what extent is the question. I do appreciate your question and the conversation that's followed here.

In my simple mind, while I was in the powertrain warranty period, I would use the specified "non-racing" use case viscosity since I personally don't want to "fight the fight." Again, that's me, and I acknowledge that I have not seen enough information to understand any long-term impact in a switch. You note that the pressure is much higher, which certainly would give me pause on longevity. However, the total system might not really be affected by that, depending on the limits of strength or cooling.

Did you initially do the change for noise or another reason?
 

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I have a 19 Bullitt and I recently changed to a 5W30 at 11k miles and I don't hear the rattles, also I have and app on my android called Torque and I can record video while I'm driving with all the gauges I want on the screen, my app connects to the OBDII via bluetooth and send the signal to my app and I can track the HP at the wheel in real time also Rear axel torque, while I was driving with the oil 5W20 my max HP was 450hp and 430 ft/lb and now with 5w30 I have 517hp at the engine and 492ft/lb, is quiet engine but strong in responds. the app ask you for all the info of your car, and need to be correct to have the real readings on the gauges, I recommend this App

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To the guy that’s getting 100 psi oil pressure with the 30 weight oil, dude that’s too high! Go back to the recommended 20 weight. You’re going to have problems. To the guy that got a 67 HP increase with an oil change, dude what are you smokin’? That app you love is lying. I have been a professional mechanic for over 50 years, built and raced engines and I KNOW what it takes to add 67 HP to an engine and it is NOT higher viscosity oil! All Fords use 5w20 oil, period. Racing calls for higher viscosity, fine. Sustained high RPM demands more from any engine. Your commute does not. Goodguys autocross is NOT racing, BTW. You should ALL be using full synthetic in WHATEVER you drive and whatever viscosity it says on the oil cap, THAT’S what you should be using. Why do you think you’re smarter than the manufacturer? I have used Mobil 1 in all my cars and truck since it was developed. I put multiple hundreds of thousands of miles on my vehicles and use them hard, including my ‘08 Bullitt (And its 315 HP can still get it sideways in the first 3 gears!) Okay, sorry for the rant, I’m done.
 

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The viscosity debate can rage on. For me, oil temperature is just as important. With ten quarts of oil in the pan, it probably takes at least twenty minutes under normal driving to get your oil up to operating temperature to provide the best lubrication. Under racing conditions, oil can run up to 40 degrees hotter and hence higher viscosity is required.
As a Master Tech. since 1980, I too recommend full synthetic oil. Especially for cold starts, where you need good flow to moving parts quickly. In the quest for better fuel mileage manufacturers are going to lower viscosity oils. Spoke to a Castrol rep. recently who said Honda will soon be using 0W10 oil as OE. Wow.
 
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