I no the 05 and up mustangs call for 5w20 oil, but i heard that 5w20 oil is to thin for the engine and will lead to engine damage in the future. I am hearing now that the new 3 valve engine tolerances need the 5w20 oil because of the variable cams and that if you use 5w30 or thicker the engine will not run right. I would like to use Mobil1 5w30 in my car for the extra protection. Are any of you guys running 5w30 in you cars with no problems?
can you use 5w30 in the 05-up mustang?
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If you grace the 4.6 (pre-2005) forums at all, you'll see this topic there, too.
You're fine with 5w-30. Ford, et al, chose to move to 5w-20 to lower the fleet's fuel consumption rates to shine better when measured against CAFE standards.
You're fine with 5w-30. Ford, et al, chose to move to 5w-20 to lower the fleet's fuel consumption rates to shine better when measured against CAFE standards.
GOLDENPONY
Founding Member
OIL
I'm sure either oil is fine. I trust Ford when they specify the 5W20, I have no problem using it. I use 5W20 Mobil 1.
I'm sure either oil is fine. I trust Ford when they specify the 5W20, I have no problem using it. I use 5W20 Mobil 1.
As an ex Ford tech... if your motor blows under warranty, they will test the oil for the correct viscosity (5w20) before doing any work.... It's a big deal to them. Honda and Ford went in together and spent millions in making this new oil, and there is a reason it says 5w20 on the oil cap. 
Hey PoopDawg
Since you were a ex ford tech,have you heard anything about having to use 5w20 because of the tight tolerances in the variable cams or did ford and honda do this to get better fuel mileage and look good for the epa. I just think it is to thin and want some extra protection in the 5w30.
Since you were a ex ford tech,have you heard anything about having to use 5w20 because of the tight tolerances in the variable cams or did ford and honda do this to get better fuel mileage and look good for the epa. I just think it is to thin and want some extra protection in the 5w30.
I was always told it was for the tight production tolerances. I COULD be wrong, but that is the only thing I could think it would be for. Going from 5w30 to 5w20 isn't going to give you any significantly better gas mileage. There is little, to no windage in a mod motor, anyway. All I know is use 5w20 or you'll be 
Even the non Ford dealer shops I have worked at always carried bulk 5w20 because of Ford and Hondas demands to always use that weight oil.
Even the non Ford dealer shops I have worked at always carried bulk 5w20 because of Ford and Hondas demands to always use that weight oil.I was always told it was for the tight production tolerances. I COULD be wrong, but that is the only thing I could think it would be for. Going from 5w30 to 5w20 isn't going to give you any significantly better gas mileage. There is little, to no windage in a mod motor, anyway. All I know is use 5w20 or you'll be
WERD!
if an engine blows with other than stock specified oil grades they can kick you in the ass and send you on your way with a fat bill for a new engine. You could probably fight it in court and win proving that a 5w30 oil is plenty sufficient for the motor, but its worth it to just use 5w20. whats the big deal anyway?
GOLDENPONY
Founding Member
Oil
Don't confuse thin appearing oil with no protection. The oils of today are so much better, they don't need to look like STP to do the job. 5W20 is picked up by the pump and gets to where it needs to be so much faster at startup, and thats when most of the wear occurs-at startup.
Don't confuse thin appearing oil with no protection. The oils of today are so much better, they don't need to look like STP to do the job. 5W20 is picked up by the pump and gets to where it needs to be so much faster at startup, and thats when most of the wear occurs-at startup.
What? Are they going to test the viscosity of the used oil and make any real determination of the original viscosity? I doubt it. Now...will they point a finger at your CAI, and tune? You bet!
What? Are they going to test the viscosity of the used oil and make any real determination of the original viscosity? I doubt it. Now...will they point a finger at your CAI, and tune? You bet!
Actually, they do. It's worth it to them to check it rather than dish out a brand new engine. As i work as a mechanical engineer, and deal a lot with replacing faulty hardware and complaints from customers. If they modified it in anyway, we tell them to take hike. Thats business, and it costs us a lot to replace parts at MFG cost. Now, are parts are pocket change compared to an engine, and would check oil viscosity in 2 seconds if an engine blew and was held responsible for replcing it.
But, you are right. They crap a brick at the site of an intake, but an aftermarket tune does automatically void warranty to the computer, and to end. Now, if you had a tune an a rod bent, they could not pin that on you.
anyways,
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