Oil weight general question


Old 06-28-05, 03:03 PM
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Oil weight general question

Have a 87 Mustang 4 cyclinder with 102K miles. When idling, oil pressure gauge drops down close to 0 but goes up after moving again. Pressure is higher when first starting the car. Is it posible to use different weight oil on older vehicles? Why does pressure drop on older vehicles?

Also have rumbling vibration from the engine when first starting the car but just when putting it in reverse. After it's warm, problem goes away in reverse. Just had the trans rebuilt and took it back. They said the trans is fine and even tried a different one but it didn't help. Not sure what to think.

thanks for the help
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Old 06-29-05, 04:56 AM
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pressure can drop from a couple of different reasons one possibility is that the oil pump is getting worn and unable to put out adequate pressure.
the other possibility and probably the most common reason on vehicles with some mileage on them is excessive bearing clearances as the clearances in the engine bearings get wider from wear it will lower the pressure as their is less restriction to oil flow and in this case changing the oil pump doesnt usually help the problem at all.
you can use a different weight oil but even a heavier weight oil will not make much of a change in oil pressure on a fully warmed up engine, but could affect the pressure by a couple of psi.
check exhuast.
Old 07-01-05, 01:08 PM
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You should first check the pressure sender. A shop can hook up a pressure guage in its place or you can just go ahead and replace it. It shouldn't be too expensive. Not to say your engine concerns aren't valid, but nine times out of ten it is the sender, especially if the engine runs okay otherwise and isn't using oil.
Old 07-04-05, 11:44 AM
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Will give it a try, thanks for the info.
Old 07-04-05, 06:11 PM
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A common complaint from this vintage Mustang
Ford addressed the problem in later models and eliminated the complaints
They installed a gauge (sender actually) that read normal no matter what the oil pressure actually was
No kidding

You should check it to be sure, but here's a good chance it's the sender
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