Utah Girl needs Help! Rough Idle and odd Oil Light, Please before my husband breaks something

I have two questions. We inherited a Caddy (98 white) a few years ago, but in the last two days it has started to idle very roughly. The idle speed goes up and down and it feels a bit like a washer that is off balance. My husband, he does try, spent 30 dollars and stuff to add to the gas tank but it didn’t help.

Second question. Our Dodge Minivan, (99 White) when ever it is at a stop light the oil light comes on with the horrable dinging. It only does it after the engine has warmed up. It never does it in park or when I am driving. And at the stop light I can make it go away by reving the engine up to 1000 or so.

Thank for your help

The stuff he has added to the gas tank is some Techron stuff and something called 107 oxtane boost.

Caddy: Is the check engine light on or flashing? If so, take it to a parts store like AutoZone and they will read the codes for free, then post back with the code (something like P0123). Don’t just tell us their recommendation, ask for the printout from their computer and give us the info, you will get a better answer(s) that way.

If there is no check engine light, look for a disconnected vacuum line or spark plug wire.

Dodge: You have either a worn out oil pump or bad bearings. If you are using 5w30 oil, try switching to 10w30 or 15w40 diesel oil.

The Caddy, get a tune-up. New spark plugs and a new air filter.

The Minivan, engine is wearing out. Unable to maintain good oil pressure at idle in gear. Plan on replacing it within the next year.

Thankyou everybody. The check engine light did come on. Tyler’s answer when the check engine light comes on is to disconnect and reconnect the battery. The way it is running I assume that the light will come on again.

Yes, it will. Get the codes read, and post here. The car is trying to tell you what is wrong.

The oil light could also be something as simple as a bad oil pressure switch that tells the gauge what to read. I’m assuming that the oil level is correct.

You may not need to wait until the light comes back on.

The stuff your husband put into the car should not cause any damage, but it also would be very surprising if it did any good.

I would worry about that oil light and bell. It could be serious and it could be damaging the engine. What I did not read was your comment about you or your husband checking the oil level. That should have happened the first time it happened and I would not have waited until I got home, I would have pulled off to the side of the road and checked it then

I would also suggest that the maintenance be caught up if it is behind.  This would likely include oil change air and fuel filters spark plugs and likely wires, maybe automatic transmission fluid if it is over 50,000 miles etc. 

 [b] I suspect that checking the oil level and doing the maintenance will take care of it. [/b]

On Dodge in order to diagnose you need a mechanical oil pressure guage on the motor. This will tell if your oil light is electrical(minor) or mechanical which the likely case your van engine will be junk soon.