Okay I know mustangs call for 5w20 but I was thinking of using 10w30 because of the fact that I have 75000 miles. Im dont think im burning much oil but feel 10w30 synthetic might be better at this point.
Unless your car is consuming more than 2 quarts between changes I would stay with the 5w20
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Sometimes I think that government fits that old-fashioned definition of a baby: An alimentary canal with an appetite at one end and no sense of responsibility at the other.
- Ronald Reagan
I agree completely with BlueStreak03! The thicker the oil viscosity is when hot, the more the engine will wear to achieve the proper clearance for the oil flow quantity it needs to STOP wearing. Put it this way, if you put 40w oil in your engine now there would be WAY too little flow of oil to protect the bearings. You would get high oil pressure but little flow. An adequate flow of oil is what protects the bearings not pressure! The engine would adapt, as it does when you break it in to develop clearances through wear to achieve proper clearances to protect the engine with that weight oil. So all you accomplish is to wear the engine when you put a heavier weight oil in the engine. :thumbsup
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2002 Mustang GT Convertible, auto, Mineral Grey, Dark Charcoal leather, Bullitt rims.
2007 Ford F150 SuperCab FX4, Dark Shadow Grey/Black cloth, 5.4 FFV.
An adequate flow of oil is what protects the bearings not pressure!
Actually you need pressure more that flow, pressure forces the oil to make a barrier between the journals and the crank (and the cams and other parts), flow just keeps a clean supply of oil.
OK, neither one is more important than the other. Pressure is a mathematical expression of the force that causes flow. You can't have one without the other. However, you don't NEED 60psi of oil pressure. You NEED enough oil pressure to cause that adequate flow of oil to all the bearings and lifters and into the cylinders. Let's not get all wrapped up in sheer numbers here guys.
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Sometimes I think that government fits that old-fashioned definition of a baby: An alimentary canal with an appetite at one end and no sense of responsibility at the other.
- Ronald Reagan
Ok, not to get wrapped up here in numbers here but you can have one without the other. There is 32 pounds of pressure in my tire but there is no flow (unless I have a leak). Also if you put a pressure gauge at the end of a garden hose leaving the hose open ended there will be flow and no pressure. Pressure is not a mathematical expression it is a tangible force, just ask a firefighter who has to hold one of those 4" hoses to put out a fire. But you are correct in that you engine needs both in order to protect the rotating parts and prime any lifter that one might have.
They are related to each other given that the external forces stay the same, like if you buy a high volume oil pump, the pressure will be greater that a "stock" one because the orifices that the pumps are pushing oil though is the same.
I was referring to an dynamic fluid system, not a static one. Yes, in a static fluid system you can have pressure without flow. In a dynamic one you can't have one without the other.
I'm not going to carry on an in depth discussion about fluid flow in this thread. But if you had read my reply fully, you would see that you just repeated what I already stated.
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Sometimes I think that government fits that old-fashioned definition of a baby: An alimentary canal with an appetite at one end and no sense of responsibility at the other.
- Ronald Reagan
Are alot of people using 5W20 oil in their 4.6 mustangs? My owners manual says 5W30 and thats what i have been using but my car is consuming 1 -1.5 quarts of oil............a dealer said try 5W20 it might slow down the oil consumption. This is actually from another thread but can my engine be consuming or without burning it or is it the same thing? I see no smoke or leaks anywhere and car runs strong with 68,000 miles on it
Your car uses 5W30 from the factory, stick with it. Maybe switch over to an oil made specifically for higher milage cars, but stay with the recommended weight. 5W20 is called for from the factory for the 2 SOHC engines.
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Sometimes I think that government fits that old-fashioned definition of a baby: An alimentary canal with an appetite at one end and no sense of responsibility at the other.
- Ronald Reagan
Is it time to start using 10 weight oil yet? 
