What happened Oil stocks had a rough start to the week after WTI Crude oil prices fell 4.9% to $93.82 per barrel and Brent Crude fell 3.9% to $99.87 on Monday. That pulled the entire industry down. Shares of oil producer Centennial Resource Development (NASDAQ: CDEV) plunged as much as 5.6% today, offshore rig owner Transocean (NYSE: RIG) fell 7.7%, and Core Laboratories (NYSE: CLB) dropped 8.9%. The stocks closed the day down 1.8%, 4.7%, and 4.9% respectively. So what The biggest economic news out today was the Institute for Supply Management's (ISM) reading of manufacturing sentiment. The ISM's measure of manufacturing PMI was 52.8% in July 2022, indicating slow expansion in manufacturing. A reading above 50% implies growth while below 50% indicates contraction. What was concerning is that a new order reading was 48% in July, which could be bad for future growth. This was the worst manufacturing PMI reading since May 2020 when the COVID-19 pandemic was in its early stages. If manufacturing activity slows down, that's not good for oil and gas demand, which is why prices are reacting today. Prices of futures have been below the spot price -- which is what the media usually reports -- for months, so it's not surprising to see prices fall. But the market may not have been anticipating this quick of a drop. Now what The supply of oil has been slowly but surely increasing because prices have been high enough for some drilling to be justified. That's given not only oil producers hope, but also hope for service providers like Transocean and Core Labs, who only make money when oil producers need their services. As much as the market may react to a day's trading like this, I think it's more noise than investors should be thinking about long-term. Oil producers aren't worried about the daily swings in oil, and I think there's been a structural change in how aggressive companies will be investing in new production. There's been an uptick in drilling lately, but not enough to flood the market and hurt pricing like there was in 2014, which indicates that prices should remain relatively high. That should be good for oil company operations long-term. I wouldn't read too much into a single day's trading in oil markets. Prices can move up and down wildly, and today is just a down day. I still think producers are being more conservative and won't flood the market, even if there's a small slip in demand. For long-term investors, this looks like a buying opportunity. 10 stocks we like better than Core LaboratoriesWhen our award-winning analyst team has a stock tip, it can pay to listen. After all, the newsletter they have run for over a decade, Motley Fool Stock Advisor, has tripled the market.* They just revealed what they believe are the ten best stocks for investors to buy right now... and Core Laboratories wasn't one of them! That's right -- they think these 10 stocks are even better buys. See the 10 stocks *Stock Advisor returns as of July 27, 2022 Travis Hoium has no position in any of the stocks mentioned. The Motley Fool recommends Core Laboratories and Transocean. The Motley Fool has a disclosure policy.Source