What is the" major reason" for changing to a '88 Fiero oil sender ? (3 wire). (when installing a 3800SC in a 1985 fiero) I use a Mechanical oil gauge.

The "major reason" for changing to a stock 88 Fiero oil pressure sending unit when doing a 3800 swap into a Fiero is so the stock Fiero oil pressure gauge on the dash will work properly and give reasonably accurate pressure readings.

Most stock oil pressure sending units that come on 3800 engines are incompatible with the stock Fiero oil pressure gauge on the dash.

MECHANICAL oil pressure gauges are dangerous. On more than one occasion I have witnessed the mechanical oil line leak or burst inside the passenger compartment while the engine was running, and you can imagine what a mess hot engine oil can make inside the car (not to mention the risk of spraying the driver or passenger with hot engine oil, burning them). A good electrical gauge is the only way to go.

A properly working OE Fiero oil pressure gauge is reasonably accurate. Modern aftermarket electronic oil pressure gauges are more accurate and highly reliable - but they cost more. I wouldn't recommend anyone run a mechanical oil pressure gauge except on a farm tractor.

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"MECHANICAL oil pressure gauges are dangerous. On more than one occasion I have witnessed the mechanical oil line leak or burst inside the passenger compartment while the engine was running, and you can imagine what a mess hot engine oil can make inside the car (not to mention the risk of spraying the driver or passenger with hot engine oil, burning them). A good electrical gauge is the only way to go."

I Couldn't agree Less. The only lines that break are if someone is silly enough to use that Nylon garbage that comes with the gauge. I 've been using copper for 40 years, never had a problem .( the nylon gets brittle, it "Kinks", then cracks) I've never seen a really accurate electronic gauge. Surely Not from the factory.
I'll wire in the '88 setup ( in the midst of making the harness). I thought the oil sender had something to do with the Fuel pump also,(Or is that Not the case when doing the swap ?)

quote Originally posted by Lou6t4gto: I Couldn't agree Less. The only lines that break are if someone is silly enough to use that Nylon garbage that comes with the gauge. I 've been using copper for 40 years, never had a problem .( the nylon gets brittle, it "Kinks", then cracks) I've never seen a really accurate electronic gauge. Surely Not from the factory. I'll wire in the '88 setup ( in the midst of making the harness). I thought the oil sender had something to do with the Fuel pump also,(Or is that Not the case when doing the swap ?)

Everyone is entitled to their own opinion. But I have seen my share of leaky mechanical gauges, some with that cheap plastic nylon line, and even some with copper lines. I'm sure some of the leaks were due to lack of maintenance, but you can chalk that up to just one more thing that has to be checked periodically on the car (along with everything else). And in a Fiero swap, you are going to have a mechanical oil pressure gauge line that is much longer than it would be in most cars = just more chance of a problem, in my opinion.

I've seen quite a few aftermarket mechanical oil pressure gauges that weren't accurate as well. So just because it is mechanical doesn't mean it is 100% accurate. Depends a lot on the quality of the gauge and the age of it. They do go bad over time.

But it is your car and you can use what you want. All I'm saying is a properly working electrical gauge and sending unit (even an OE Fiero one) can be reasonably accurate - if they are working properly.

[This message has been edited by Darth Fiero (edited 11-06-2013).]