What are some good quality conventional Motor Oil brands?

my car has about 180k. Ive been going to firestone where i pay for the cheapest one so im guessing they're poor quality.I also dont get the difference with 5w-30 or 4w-20 and all that. I dont really need an explanation but rather a recommendation.What are some good quality conventional Motor Oil brands?
VALVOLINE or CASTROLWhat are some good quality conventional Motor Oil brands?
Quaker State............Pennzoil
Never use what isn't recommended by your engine. The engine oil weight shouldn't be messed with. Your car will either have 5W30 or 10W30.





Mobil 1 Tri-Synthetic is a good motor oil... for higher compression engines (comes factory in Corvettes, Lambourghini, Ferrari and Porche), but in a car with 180,000 plus miles, not recommended.





Quaker State has a higher mileage oil for cars with 150,000 miles or more... like your car.





Although Mobil 1 is like liquid plastic, you don't need it. Use Quaker State High Mileage.





Next, don't go to Firestone. They are a national dealer whose only goal is sales. Usually hiring lower quality technicians. Best bet is to go to your local garage or dealership. It may cost more, but you get more.
I recommend MOBILE 1 brand. I used to use Castrol GTX but when I switched to mobile 1 I felt the difference. I also use 1 32 oz. bottle of Lucas oil stabilizer every time I change my oil.





The 5w-30 is the weight and protective properties in the oil. Newer cars only need a 5 weight (w) because they are designed to be ran with that weight, but older cars can benefit from a little heavier weight like 10w or a 20w. Just remember the heavier the weight of the oil the more your oil pump works. If you want to prolong the life of your engine you should use mobile 1 high milage and maybe a bottle of Lucas oil stabilizer. Probably a 10w-30 or a 10w-40. I hope this helps!
Its all pretty much the same anymore. Some maybe cheaper yes, but for the most part they are alot alike. I use Valvoline 10-30 in winter and 10-40 in summer. Manufacture suggest 5-30 all year around. I have 133,000 mi on my cav z-24 and not a lick of oil dripping, leaking or burning. Car runs like it did when i pulled her off the lot 6 years ago. The biggest part of oil is the changing. I change mine every 2000-2500 miles. religously. The filters are one of the major players in the oil story. Cheap filters can be catastrophic. Case in point, we buy oil filters in bulk for our vehicles, being government we have to go with lowest bidder. They were a grey filter, something in german i believe, well we went to change oils and one filter after another had metal in the exit side of the filters! had we used those our vehicles would have been junk. Now we use Mobil 1 filters or fram.