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Anybody else have to raise their idle to keep the oil light from coming on? I dropped the idle down to 900 rpms where it is supposed to be and the oil light came on and stayed on when my foot was not on the gas. So I inched the idle up until the light stayed off during idle, and this seems to work. I would love to figure out what is going on though and be able to set the idle down at 900 again if I could.

The oil is about halfway up between the add and full lines.

Any suggestions? I thought maybe my (fram) oil filter is bad, or maybe the oil sending unit.

I would first suggest adding a oil pressure gauge so you can actually see what the oil pressure is doing.

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03Cobra

How many miles on the engine? Idiot lights were never much help when trying to diagnose a problem. A direct reading gauge tells you more.

This happened on (one of the many) a LUV truck that my dad used to own. If you have a lot of miles on the truck, your problem can most likely be found in your cam bearings. If they get too worn, the cam will settle down at idle and allow the oil to pour through the bearing, down the back side of the head (inside the engine of course). Because it is redirected in this fashion the oil sending unit senses a drop in pressure. Idling the motor up slightly puts enough tension on the timing chain to straighten the cam out such that the oil goes down the correct passage ways where the oil sending unit is, instead of down the backside of the head.

When was the last time you changed the oil? Fresh oil and a new filter might help some. Also you might concider going with a heavier weight oil to keep things good.

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Previous setup: 4.1 Buick V-6/TH 350
Current setup: 400 Small Block Chevy V-8/TH 350
9" ford rear end/short bed/blue
What do Water, Electricity and Humans have in common... They all travel the path of least resistance.

Oil pump too, and or bearings.

either way whatever is causing the oil light to come on, you're gonna have to do a rebuild soon.....I'd go ahead and do it before you spin a bearing or sumptin worse

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Well, I changed the oil and filter. Used 20w-50, and a purolator instead of fram. Dropped the idle back down and the oil light is not coming on anymore at idle. Does that make sense to you guys?

Also, I bought an aftermarket oil pressure gauge. When I went to install it, I found out quickly that the original sending unit has a metric thread going into the block, and the new oil pressure gauges are all standard 1/8" pipe thread. I tried to find an adapter, but couldn't find one anywhere. Anybody else run into this problem before?

GetWillie,
The Japs use a British thread I think its called out 1/8BSPTF or 1/8BPTF British stndard pipe tread fine TO A a 1/8NPTF thats the adapter you need.
The one in those kits are 1/8NPTF I believe. I have a 2 510s and a 521 truck.
I found some oil pressure adpters and bought a bunch of them.
I found them at B&B autoparts in Renton,Wa but found them in the back with all the odd fittings. The guy who worked there didnt really know whathe had just showed me the oil gauges and those cheazzy kits.

I tried the smaller napa stores but might have to look in one of there books to order it or have a specifec #.

Also Buy a good Gauge. Out of the cheap gauges the VDOs and the Steward warners are the better ones compared to the autogage models witch are the bottom of the line ones I wouldnt put on my lawn mower. But what is worst is the plastic line. Get a true autometer oil line. The cheap taiwan ones will crack after awhile. due to the hot and cold oil. Maybe a copper tube would be better or a electric(transducer type) would be better.
I keep a spare stock oil pressure sender just incase the line will break so I get plug it if needed.

Maybe scam a gauge out of aDatsun Z car or a rabbit(VDO).older Mercedes ect.
The new VDOs that are sold ,the gauges are all Malaysian made and the cheap Steward Warner I had was Mexico I believe. But better than those Schuck Jobs.
The autometer look good but the the better ones are th big dial witch I dont really need.

Update.
The jap cars use(Datsuns) assume other will use a 1/8-28 BSP(british standard pipe).

So you want a oil adpater thats a 1/8NPTF X 1/8-28 BSP to fit in the block.
The 1/8NPTF will fit most of the chessey oil pressure gauge kits. seems they dont work with the fitting they come with.

I got mine from B&B autoparts in Renton ,Wa
part # 207907 In a bin in back(obsure) It WASNT with there typical high quality guage kits(yeah Taiwain junk)

Hey Getwillie, I just went through this same scenario and changed the oil light went off but came back on during a hot day. I adde a bottle of "Motorhoney" and that turned it off for a week or so till it was 95 degrees out and had been driving for like and hour. Ultimately I changed the motor out and WOW, lots more power and no flashing oil light. Now the motor sits on my engine stand waiting to be torn down to see what the source of the low oil pressure was. Sorry to bring the bad news, but you could try changing the sending unit first before pulling the motor. Might turn out the light and a new sender can't cost that much.

I see a lot of sending units go bad... if you remove the sensor and test it with air pressure you can hook a multimeter to it and determine when it opens by slowly increasing the pressure till the multimeter reads open circuit. should be arround 20 psi. however thats why i dont always trust these lights. install a manual gauge and watch it. if its reading low then there is obviously a mechanical problem. my luv 1.8 usually gets new main and rod bearings each year. its prior owner did not take care of the engine and damaged the crank slightly. however i think a set of bearings per year is a small price to pay for 30mpg highway and 26mpg city.