I have a 1994 Dodge 1500, 5.2, 170,000 miles and I swear there seems to always be something wrong with it, even though I love it.

About six months ago I noticed, speratically, the oil light would come on at a complete stop/idle, and as soon as I would hit the gas it would go away. At first the oil pressure would remain normal. It would happen so rarely that I would just check the oil, add some if needed and go on my way.

About two months ago it got really bad where the light would constantly turn on any time i was idle, as long as the truck was warm. Then my oil pressure gauge would jump around from zero to normal. I changed the oil and oil pump and didn't have any issues afterwards.

I was also having RPM issues relating to a clogged catalytic converter. Today I picked up my truck from the exhaust shop after getting a new exhaust/catalytic converter. I was in Alaska when all this took place and now I am in Texas (104 degree heat). After driving around for a bit, I noticed my oil light popped back up once the truck was warm and I was at an idle.

I bought 10w40 oil as I figured a thicker oil may be a fix, as the oil in it now is 10w20 I believe as it was cold until recently in Alaksa. Other than oil swap, any other thoughts? I have been reading online about similar situations and some say rod/bearings. Does this sound like my truck? There was no weird noise or oil pressure change when the light turned on, and it went away as soon as I hit the gas.

 

I had a similar situation although my oil pressure gauge was low at idle etc - I replaced the oil pressure sensor and all has been good since. It was a fairly easy $50 fix

 

I have noticed my oil pressure does move a bit from a hair below normal to a hair above when I accelerate, but it has not dropped to zero since I replaced the oil pump. Looks like I will swap this out when I do my Hanes plenum repair in a couple days. I figured I might as well do this as a precaution, and I love messing around on the truck. Although I prefer it be just updating everything rather than repairing everything.

 

You could also add a mechanical gauge so you know for a fact what the oil pressure is. All you need is an 1/8" short pipe nipple and a tee. Here is a picture of mine:

 

Nice! Do you mind zooming out a bit so I can see what that is hooked up to? Also, my oil pressure gauge seems to be okay, it's just the oil light. Do you think it could still just be an error fixed by knowing the actual pressure?

 

I went with the mechanical gauge because I don't trust electric gauges. This one proved me right. My gauge always stayed around 40 psi (35 to 45 roughly) but the light would come on when at idle. After putting the mechanical gauge in I found that my cold pressure was about 60 and my hot would drop to about 10 at idle. This was with delo 15-40 diesel oil.

The black thing on top is the sending unit. The line coming out the side runs through the firewall to my mechanical gauge. The blue in the back right if the photo is the distributor. Here is a panned out picture to show location a little better... if you can see it through the plug wires. Lol

 

Got it, any idea why the reassure would drop so low during idle? Sounds like mine has the same issue.

 

Generally, its just a bad sending unit. If your engine is high mileage, the gauge *might* be telling the truth..... only way to know for sure is put a mechanical gauge on it.

 

Mine was just worn out. I had changed the oil pump to a high volume, and changed rod bearings while I was in there. It helped for a little bit, but I just got use to not letting it idle to avoid bad noises.

Like HeyYou said, most of the time it is just a bad sending unit, but after my experience I usually suggest the mechanical gauge so there is no doubt.

 

How hard is changing the rod bearings once the oil pump is off. I just put a high flow pump on a few months ago.