Are there options available to retail investor to go long on crude oil price? Ideally, a liquid "oil price index" ETF that would go up or down in sync with the price of crude.
A simple google search shows several funds with such goals (e.g., on https://etfdb.com/themes/long-crude-oil-etfs/ ), but with different performance over the same time period (both daily and YTD), which looks suspicious.
Almost all of these funds will hold some combination of cash, short term debt and oil futures, with the ratios depending on their target leverage.
Performance between them will vary depending on, among other things: whether or not the ETF is levered, which particular type of crude it's tracking, it's time horizon, and how effective the fund managers are at rolling their futures holdings.
NOT investment advice. Commodities are fickle.