Is "Mobile one" a good motor oil? For a '97 s/c coupe

i'd go two quarts synthetic and two quarts conventional + .5 quarts your choice.. not full synthetic. your engine seals were not made for full synthetic. might leak a bit. my 2002 camaro did ok with that mix. use10w -30 if your engine has 50k miles +.

Boy, I don't know about that mix of oil, stay with just the straight Mobile 10w30. It is a good oil. A lot of synthetic oils do not blend with conventional oils. (petroleum oils)

It is dumb to mix oils, in my opinion, unless you are a petroleum engineer. Some additives may not be fully compatible with others. I would use synthetic named brand oil in the proper grade recommended by the manufacturer. Mobil1 is my choice for synthetics and I use Motorcraft Synthetic Blend for non- supercharged non-turbocharged applications.

Agree. Mixing oil types is a bad idea. Mobile 1 should be fine although its probably overkill for an older car like yours. What are you trying to accomplish by going to a high grade full synthetic? A decent quality semi synthetic blended for high mileage motors is probably a good choice. Then change it regularly as per the GM maintenance schedule for that car and you'll be fine. Use the weight that GM recommends for your engine. It's probably written on the oil filler cap on your engine.