What is the right type of oil to use in a 1995 cad deville 4.9 engine i use 20w 50w is that ok

SOURCE: hOW MUCH OIL GOES IN A 2000 CAD DEVILLE, 32 VALVE

It's going to take about 7.5 to 8 Quarts. All Northstar engines are like that, so no worries.

SOURCE: Oil type to use

either will be adequate. if you live in a hot temp zone run the 20/40 and if it cools off (freezing) during winter change to 5/30. Moderate year round your 20/40 will be fine. I would also use a bottle of Lucas Racing Oil treatment with the change. Don't forget your filter. I also suggest using full synthetic, yeah it costs more but worth it.

SOURCE: I have a 95 cad. deville no dash lights

the dimmer switch would be where I would look first. See if the conditions change after turning the lights brighter and dimmer.

Harvey N Tawatao

• 3854 Answers
• Posted on Jul 23, 2009

SOURCE: 2010 Vibe Type & Quanity of Eng Oil

The 5-30W gives the oil a better heat range, so when you go to Florida, the engine oil keeps it's viscosity better.
The 5-W20 has a lower heat range and is great in the upper states and canada where the temperature is not as hot as Florida or Texas.
The 0-W20 is even better if your in the colder climate like Alaska so the oil is not that thick, and when you have the start the engine first thing in the morning, the oil can move quicker to the upper part of the engine. 
Best thing is no matter what oil you use, just as long as you follow the recommended oil change duration. Your going to be fine and have a long lasting engine and also make sure you warm up the engine first before running it hard to have the piston and cylinder walls expand the same time. As you run the engine hard when it's cold, the pistons expand quicker then the cylinder walls and after a few years. The pistons and cylinder walls will have to much play and you get piston slaps till the engine warms up. 
Good luck and hope this helps and the 5-W30 is more forgiving if you go over a few miles between oil changes. 

SOURCE: 1995 Cad. Deville. Engine light on, runs rough

If you havnt had it diagnosed it could have a couple hundred codes it can be. Suggestions don't count for nothing. They just cost you more money if you dont get it diagnosed.