Bought a 1982 cadillac eldorado 4.1 v8 for my son. Did a tune up and an oil change. As soon as we started the car after the oil change the low oil pressure light came on. It was suggested that we used the wrong viscosity oil 10w40 with a qt of slick 50 so we draied it and put in 20w50 still the light is on. Any suggestions. It wasn't on before oil change.

Any possibilty you accidentally disconnected the wire to the oil pressure switch? It's right by the oil filter on my 4.9.

Just a few thoughts off the top of my head.

It would be helpful to know how many miles you have on the car and if your oil light is on all the time or just at idle. Also, when you did your tune up, did you adjust the timing or idle speed? Did you verify that you indeed do or do not have oil pressure?

The car has 40,000 miles on a rebuilt engine. The timing or idle speed was not changed. Just plugs, wires, dist. cap and rotor button. Problem seemed to stem from oil change but cant be sure. How would you check to see if you were getting oil pressure?

An easy way to check for oil pressure would be to see if oil is getting to the head. You might be able to just look throught the oil filler cap opening and see it splashing around or you can pull the valve cover itself.

Please don't waste your money on Slick50.

10w40 with a qt of slick 50

It's probably the suspended solid particles in the Slick 50 clogging your oil system. I would sooner shoot myself than use that stuff in any of my cars - Cadillac, BMW, even the Jeep.

It's been proven only to cause damage. No impartial test has EVER proven anything conclusive in the positive, only no difference or negative effects results.

Slick 50 is garbage. Put it where it belongs.

Check to make sure the oil pressure switch wire is not grounded or shorted. They have nasty connectors that tend to deteriorate. That can put the light on.

If that is OK, you can remove the sensor and check the oil pressure form that port. If it is low, then there is a good chance that some crap got stuck in the relief valve in the pump. You'll have to remove the pan to get at it.

Or, you can try a trick (or PSB) that was outlined for this for Northstars. Fill the pan with oil, at least 10 litres so that the pump becomes submerged. Then snap rev the engine to 300 rpm or so several times. This goes to dislodge what was stuck in the relief valve. Then, if the oil pressure returns, drain the oil and fill it to spec.

I would also have to second the notion of NOT using Slick 50, or any of the other snake oils. They are a money grab at best, and can cause damage at worst. The only additive that actually works is GM's own EOS. I would also recommend using one of the HD diesel 15W40 oils such as Rotella T.

Mike