ilanzo

Hi. I need to know what oil should I use for 1974 oldsmobile cutlass supreme. The engine is a bit exhausting blow by. Will a thick oil reduce the blow by and the smoke? What oil should I use?

oldcutlass

Thick oil will not cure your blow by problem and may create other issues. You need to fix the cause usually rings and valve guide/seals. Also make sure your PCV valve is hooked up and working correctly and you may need to run an additional hose on the opposite valve cover to the carburetor air cleaner base to supplement.

joe_padavano

^^^THIS. There is no magic liquid cure for a worn engine. Sorry.

texxas

It won't "fix" anything but I have seen high mileage, old worn V-8 engines filled with 20-50 Valvoline and Lucas oil treatment. I have put this in engines that used an unacceptable amount of oil and it cut the usage in half and cut down on visible oil smoke coming out of the exhaust. It is usually used as a temporary crutch to help move a car along and sell it. This doesn't repair blow by or a worn engine and it doesn't solve the problem, just passes it along to the next guy, BUT...
it has kept the 318 in my old 83 Dodge W-150 Prospector going for over 600K without a rebuild. It has no visible oil smoke and went from using 3 plus quarts of oil between 3000 mile oil changes to just a little over one quart. I started using the heavier oil around 200K miles with no apparent problems so far. I think I just jinxed it.
It will probably blow up this afternoon.

76olds

I know a guy that used 20-50 oil and a small bottle of liquid honey in a 1978 monte carlo 305 engine.

quaddriver

I dropped a 150K on a 74 supreme back in the day. I ran QS or pennzoil 10-40 only, and added a can of STP goo at each change. she held 50lbs pressure as indicated by a mechanical gauge.

that being said, if you are pushing past the compression rings - its rebuild time. .020 pistons IIRC are no longer made, .030 is a commitment to a full kit...even to rehone and new rings and knurled pistons, still means a compete removal and teardown.

Sugar Bear

Blow-by/compression leaking past the rings into the crankcase is caused by a ring and/or piston problem. The rings may be broken, worn-out or clogged. You could try Marvel Mystery Oil, Seafoam etc. soaking in the cylinders for a few days to unclog the rings, it is worth a try.

In addition to rings/pistons, smoking/burning oil may also be caused by bad valve seals, worn valve guides or clogged oil returns in the cylinder heads. Pull the valve covers and confirm that the oil return holes in the bottom front and rear corners of the heads are open and drain well.

Also confirm as previously posted that the PCV valve has vacuum to it, it is the correct one and that it is clean.

Thicker oil usually helps more with a low oil pressure problem than an oil consumption problem.

Good luck and keep us posted!!!

texxas

Get some of this for your next oil change, probably easier said than done in Israel. I tried to find a dealer in Jerusalem but came up with nothing.
http://lucasoil.com/products/engine-...oil-stabilizer
The label states, "Helps slow blow by for less pollution and oil contamination." I'd start with one bottle added to new oil and filter at next oil change service. It can't hurt to try, it will either slow the blow by or not. They claim you can use it for up to 60% of crankcase capacity, so you could feasibly go with 3 quarts Lucas and two quarts motor oil, if your engine is really bad. IF it is that bad you are on borrowed time, my friend. What displacement is your engine? Good luck.

Ozzie

If you are sure that the oil is passing the rings (only) you could try the suggestion to un-stick the rings. If the problem is due to wear or some other sort of damage, repair is the best solution.
Oldsmobile recommends the use of 20W-50 oil in the warmer climates, as yours, as long as the ambient remains above -7C.
Do a good diagnosis. Don't forget to get the zinc compound in the oil.